WO1995015556A1 - Procede de production d'un support d'enregistrement magnetique - Google Patents

Procede de production d'un support d'enregistrement magnetique Download PDF

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Publication number
WO1995015556A1
WO1995015556A1 PCT/JP1994/002014 JP9402014W WO9515556A1 WO 1995015556 A1 WO1995015556 A1 WO 1995015556A1 JP 9402014 W JP9402014 W JP 9402014W WO 9515556 A1 WO9515556 A1 WO 9515556A1
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WO
WIPO (PCT)
Prior art keywords
filtration
paint
recording medium
dispersion
magnetic
Prior art date
Application number
PCT/JP1994/002014
Other languages
English (en)
Japanese (ja)
Inventor
Shigeo Kurose
Yoshihiro Honjo
Akira Somiya
Original Assignee
Tdk Corporation
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Tdk Corporation filed Critical Tdk Corporation
Priority to KR1019950703009A priority Critical patent/KR100283522B1/ko
Priority to DE69432923T priority patent/DE69432923T2/de
Priority to EP95902279A priority patent/EP0684597B1/fr
Publication of WO1995015556A1 publication Critical patent/WO1995015556A1/fr

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Classifications

    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/62—Record carriers characterised by the selection of the material
    • G11B5/73—Base layers, i.e. all non-magnetic layers lying under a lowermost magnetic recording layer, e.g. including any non-magnetic layer in between a first magnetic recording layer and either an underlying substrate or a soft magnetic underlayer
    • G11B5/735—Base layers, i.e. all non-magnetic layers lying under a lowermost magnetic recording layer, e.g. including any non-magnetic layer in between a first magnetic recording layer and either an underlying substrate or a soft magnetic underlayer characterised by the back layer
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/84—Processes or apparatus specially adapted for manufacturing record carriers
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/84—Processes or apparatus specially adapted for manufacturing record carriers
    • G11B5/842—Coating a support with a liquid magnetic dispersion

Definitions

  • the present invention relates to a method for manufacturing a magnetic recording medium.
  • kneaded magnetic paints usually contain undispersed materials such as ferromagnetic powders and binders, as well as balls and the like. Since foreign materials such as friction powder from the kneading container are contained, the paint should be passed through a filter immediately after kneading to remove them, and then dispersed using an AC dispersing device or sand mill. It is described that the treated paint is passed through a filter to remove abrasion powder and undispersed substances generated by a sand mill.
  • the publication does not describe a specific configuration such as a filter hole diameter.
  • JP-A-53-133405 discloses a method of applying a magnetic paint while passing through a filter paper (pore size: 1 m, 4 urn).
  • pore size 1 m, 4 urn.
  • the gazette merely describes the pore size, and the clear definition of the pore size is Not listed.
  • Japanese Patent Application Laid-Open No. 54-143118 discloses that binders, solvents, solutions, etc., excluding pigments composed of magnetic powder, are used to reduce the pigment particle size (about 0.05 to 5 / m). After passing through a filter having a mesh and dispersing the pigment in the solution, the solution is filtered through a filter having a mesh equal to or larger than the particle size of the pigment, and the magnetic paint is applied on an aluminum substrate. A method is disclosed.
  • Japanese Patent Application Laid-Open No. 57-147 4134 discloses that after removing insoluble matters such as agglomerates of magnetic powder and fragments of kneading balls from a magnetic paint by centrifugal separation, the average pore diameter is 5 mm.
  • a method of filtering with a membrane filter of at least urn is disclosed.
  • the publication does not describe the definition of the average pore size.
  • Japanese Patent Application Laid-Open No. 58-103232 discloses a method for reducing bit errors by passing a magnetic paint through a metal filter (having a hole diameter of 2 m or less) and applying it on a substrate. Is disclosed.
  • Japanese Patent Application Laid-Open No. 59-586631 discloses an apparatus for circulating a magnetic paint in a paint tank through a filter provided outside the paint tank. Absent.
  • Japanese Patent Application Laid-Open No. 59-1171737 discloses that after kneading and dispersing a magnetic paint, the paint is stabilized by stirring with a filter having a pore size of 3 urn to stabilize the paint.
  • a method for reducing bit errors by filtering through a 0 nm membrane filter is disclosed.
  • Japanese Patent Application Laid-Open No. Sho 61-8223331 discloses that a magnetic paint is filtered through a filter having a pore of 3 to 5 ⁇ , then coated and calendered to a thickness of 4.5 ⁇ rn. To produce an audio tape having a magnetic layer of
  • Japanese Patent Application Laid-Open No. Sho 61-248480 discloses that a magnetic paint is treated with ultrasonic waves. A method of filtering and then applying is disclosed. The publication states that a 10 / zm filter was used, but the definition of pore size is not clear.
  • Japanese Patent Application Laid-Open No. 61-127927 discloses a method in which a magnetic paint is cooled to about 20 or less, passed through a filter, and then returned to room temperature and applied.
  • FIG. 2 of the publication discloses a device that allows the magnetic paint to pass through the filter a plurality of times, but does not describe the pore size of this filter.
  • Japanese Patent Application Laid-Open No. 62-64040 discloses that after a magnetic liquid is passed through a first ultrasonic tank with a built-in filter and dispersed at the same time as an ultrasonic wave, a part of the magnetic liquid is transferred to a second ultrasonic tank. Dispersion by ultrasonic waves again through an ultrasonic tank with a built-in filter and simultaneous filtration, or re-dispersion processing through an ultrasonic tank and subsequent filtration with a filter are disclosed It has been.
  • the publication discloses an apparatus for circulating a magnetic liquid through a filter, but does not describe the pore size of the filter.
  • Japanese Patent Application Laid-Open No. Sho 62-13434827 discloses a method of preparing an abrasive dispersion liquid containing an abrasive and a binder in advance, and then mixing the dispersion with a ferromagnetic powder.
  • the gazette discloses that the magnetic paint is filtered through a filter having an average pore diameter of 0.5 to 1.5 Mm and then applied.In the embodiment, a filter having an average pore diameter of 1 ⁇ is used. A 3m thick 8mm video tape after drying is manufactured. Then, the number of drop filters was measured using an 8 mm video recorder, and a result of 5 drops was obtained.
  • the publication does not describe the definition of the average pore size.
  • Japanese Patent Application Laid-Open No. 62-2588716 discloses a filter device in which a stirring blade rotating near a filter material is installed in a housing of a filter for filtering magnetic paint.
  • Material of filter used in Examples of the publication Is made of cellulose + epoxy resin with a nominal removal rate of 2-5 Mm. However, it is unclear what the nominal removal rate described in the official gazette specifically means. ,
  • Japanese Unexamined Patent Publication (Kokai) No. Sho 63-32187528 discloses that a gel-like undispersed material is passed through an internal capture filter having a mesh diameter of 40 to: 100 nm by the weight of magnetic paint.
  • a method has been disclosed in which after removing coarse foreign substances, the mixture is filtered and applied with a precision filter so that the gel-like undispersed matter can be reliably removed. This publication does not describe the pore size of the precision filter.
  • Japanese Patent Application Laid-Open No. 1-106331 discloses that in a magnetic recording medium having a first magnetic layer and a second magnetic layer provided in this order on the surface of a non-magnetic support, the thickness of the second magnetic layer is reduced. It is disclosed that electromagnetic conversion characteristics and running durability can be improved by setting the average particle size of the abrasive having a Mohs hardness of 6 or more contained in the second magnetic layer to be less than 0.5 ⁇ and the average particle diameter of the abrasive having a Mohs hardness of 6 or more being 0.5 m or less. Have been.
  • the coating liquid for forming the first magnetic layer and the coating liquid for forming the second magnetic layer were each filtered through a filter having an average pore diameter of 1 m, and then dried to a thickness of 0.
  • a second magnetic layer is applied to have a thickness of 25 ⁇ , 0.45 ⁇ , or l / xm (comparative example) to produce a magnetic tape.
  • the electromagnetic conversion characteristics (Y / S / N at 4 MHz) and running durability (still life) are measured.
  • the publication does not describe the definition of average pore size.
  • JP-A-2-873226 discloses that a magnetic paint prepared by passing through a 1 ⁇ mesh filter is applied to a dry layer thickness of 3 ⁇ , and a VHS cassette or an 8 mm video cassette is applied. Making is disclosed.
  • Japanese Unexamined Patent Publication No. 2-2700125 discloses that the upper layer of a magnetic layer composed of two layers has a thickness of 0.5 m or less, and the ferromagnetic metal powder contained in the upper layer has a particle length of less than 0.5 m.
  • a vertically oriented magnetic recording medium having a needle-like ratio (particle length Z particle width) of not more than 0.1 m and a needle length of 1 to 3 or less is disclosed.
  • the upper layer paint and the lower layer paint were each filtered through a filter having an average pore diameter of 1 m, and then the upper layer having a thickness of 0.29 ⁇ or 0.5 ix m was formed.
  • the publication does not describe the definition of the average pore size.
  • Japanese Patent Application Laid-Open No. 3-31616 discloses that the temperature of a magnetic paint is adjusted to a range of 10 to 20 at the time of filtration with a filter, so that the flowability of gel-like undecomposed matter and insoluble matter can be improved. A method is disclosed in which the flexibility is reduced so that these can be sufficiently captured by a filter.
  • This publication discloses that as a conventional technique, a magnetic paint is filtered with a filter having an absolute filtration accuracy of about 1 to 30 ix m.
  • This publication discloses a device in which a part of the magnetic paint after filtration is circulated through a boule tank and then re-filtered again. There is no description about the pore size of the filter for filtration. In addition, the publication does not describe the definition of absolute filtration accuracy.
  • magnetic recording media are required to have a smoother magnetic layer surface and higher running stability as recording signals have shorter wavelengths and higher densities. For this reason, the back side of the magnetic layer forming surface is required.
  • a method of applying a back coat layer to the substrate is used. If the coating for the back coat layer contains resin insolubles, undispersed or re-agglomerated materials such as conductive pigments and various abrasives that are often added, and solid impurities mixed in during the manufacturing process. However, when the back coat layer is formed, the surface of the back coat layer becomes a defect, impairing the running property of the magnetic recording medium and the smoothness of the surface of the magnetic layer, resulting in an increase in drop rate and an increase in error rate. For this reason, the following proposals have been made regarding the filtration of the paint for the backcoat layer.
  • the paint for the back layer is Before and after the adjustment, the mixture is filtered through a filter having an average grain size of 0.5 ⁇ m, and a 1 ⁇ m or 0.6 ⁇ m thick backing layer is formed using this paint. We are making. And they measure the dropout of these videotapes.
  • the publication does not describe the definition of the average particle size of the filter, nor does it describe the definition of the criteria for determining drop droplets.
  • the coating for the magnetic layer is not filtered.
  • Japanese Unexamined Patent Publication (Kokai) No. 60-698333 discloses that a paint for a backing layer after adding a dispersion liquid for viscosity adjustment and a crosslinking agent and stirring the mixture is coated with a voylene terephthalate ( ⁇ ) by a coating apparatus. It describes that, when the composition is coated on a sheet made of ⁇ ) and a backing layer having a thickness of 0.2 to 5.0 m is formed, filtration with a filter paper is performed before coating. There is no description in this publication regarding filtration accuracy such as the hole diameter of this paper. In this publication, the defect rate is measured for the VHS tape on which this backing layer is formed.
  • the defect rate in this case is the number of defects per minute for which the level down of 20 dB or more continues for 15 ws or more, which is a so-called dropout.
  • the defect rate is 5 to 10. According to the publication, the coating for the magnetic layer is not filtered.
  • the objects of the present invention are, firstly, that the dropout immediately after production is small, the dropout with time and the deterioration of electromagnetic conversion characteristics are small over time, and the durability of the coating film such as the magnetic layer is good.
  • a magnetic recording medium is provided.
  • Embodiment 1 is the following (1) to (2).
  • a magnetic recording medium having at least two coating films on at least one surface of a non-magnetic support, wherein the uppermost coating film is a magnetic layer having a thickness of 0.1 to 0.8 ⁇ .
  • the step of preparing the coating material for the uppermost coating film includes a coating step of filtering the coating material by at least one filtering means, and the 95% cut of the final filtering means in the coating filtering step.
  • the step of preparing the coating material for the coating film of the uppermost layer includes a kneading step of kneading the solid content and the binder solution, a dispersing step of dispersing the solid content in the kneaded material obtained by the kneading step, and The method for producing a magnetic recording medium according to the above (1), further comprising a viscosity adjusting step of adding a viscosity adjusting liquid to the dispersion obtained in the step to obtain a coating material.
  • Embodiment 2 is the following (3) to (4).
  • the process of preparing the paint for the uppermost coating film includes a paint passing process in which the paint is passed through at least one filtering means, and the 95% cut filtration of the final filtering means in the paint filtering process.
  • a method for manufacturing a magnetic recording medium having an accuracy of 10 times or less of the shortest recording wavelength, 6.0 ⁇ or less, and 1.0 ⁇ or more.
  • the step of preparing the coating material for the coating film of the uppermost layer includes a kneading step of kneading the solid content and the pinda solution, a dispersing step of dispersing the solid content in the kneaded material obtained in the kneading step, and the dispersion step (3)
  • the method for producing a magnetic recording medium according to the above (3) further comprising a viscosity adjusting step of adding a viscosity adjusting liquid to the dispersion obtained in the step to obtain a paint.
  • Aspect 3 is the following (5) to (9).
  • a magnetic layer on the surface of the nonmagnetic support having a backcoat layer formed by coating on the backside of the nonmagnetic support, and having a thickness of the backcoat layer of 1.0 ⁇ or less;
  • a method of manufacturing a magnetic recording medium wherein the step of preparing a paint for the backcoat layer includes a paint passing step of passing the paint by at least one filtration means,
  • a method for producing a magnetic recording medium wherein the final filtration means has a 95% cut-off accuracy of not less than 1. O / xm and not more than 6.0 ⁇ and not more than 10 times the thickness of the back coat layer.
  • the step of preparing the coating material for the back coat layer includes a dispersing step of dispersing a solid content in a binder solution, and a viscosity adjusting step of adding a viscosity adjusting liquid to the dispersion obtained in the dispersing step to obtain a coating material.
  • the method for producing a magnetic recording medium according to the above (5) comprising:
  • the magnetic recording medium has at least two coating films on the surface of the non-magnetic support, and the uppermost coating film is a magnetic layer having a thickness of 0.1 to 0.8 ⁇ ,
  • the step of preparing the paint for the uppermost coating film includes a paint filtration step of filtering the paint by at least one filtration means, and the 95% cut filtration accuracy of the final filtration means in the paint filtration step.
  • the magnetic recording medium has at least one coating film on the surface of the non-magnetic support, and the uppermost coating film is a magnetic layer;
  • the step of preparing the paint for the uppermost coating film includes a step of filtering the paint by filtering the paint by at least one filtering means, and the 95% cut of the final filtering means in the step of filtering the paint.
  • the step of preparing the coating material for the coating film of the uppermost layer includes: a kneading step of kneading the solid content and the binder solution; a dispersing step of dispersing the solid content in the kneaded material obtained in the kneading step; (7) or (7) having a viscosity adjusting step of adding a viscosity adjusting liquid to the dispersion obtained in the step to obtain a coating material.
  • Aspect 4 is the following (10) to (14).
  • the step of preparing the coating material for the coating film of the uppermost layer includes a kneading step of kneading the solid content and the binder solution, a dispersing step of dispersing the solid content in the kneaded material obtained in the kneading step, and a dispersing step.
  • the 95% cut accuracy is more than 15 urn in all cases, and the 95% cut accuracy of the final filtration means in at least one of the kneaded matter filtration step and the dispersion filtration step is 80 ⁇ .
  • the following method for manufacturing a magnetic recording medium is 80 ⁇ .
  • the magnetic recording medium has at least two coating films on at least one surface of the nonmagnetic support, and the uppermost coating film has a thickness of 0.1 to 0.8 ⁇ .
  • the step of preparing the paint for the uppermost coating film includes a paint filtration step of filtering the paint by at least one filtration means, and a 95% cut ripple of the final filtration means in the paint ripple step.
  • the step of preparing the paint for the uppermost coating film includes a step of passing the paint through at least one filtering means, and a step of 95% cut of the final filtering means in the paint filtering step.
  • the magnetic recording medium has a back coat layer formed by coating on the back surface of the non-magnetic support, and the thickness of the back coat layer is 1.O Atm or less,
  • the step of preparing the paint for the back coat layer includes a dispersion step of dispersing solids in a binder solution, and a viscosity adjustment step of adding a viscosity adjusting liquid to the dispersion obtained in the dispersion step to obtain a paint
  • the method has a filtration step of the dispersion in which the dispersion is filtered by at least one filtration means, and the 95% power filtration accuracy of the final filtration means in the dispersion filtration step is as follows. 15.
  • the step of preparing the paint for the back coat layer has a paint passing step of passing the paint through at least one filtering means, and cuts 95% of the final filtering means in the paint passing step.
  • the filtration accuracy is not less than 1.0 m and not more than 6.0 am and not more than 10 times the thickness of the pack coat layer.
  • Embodiment 5 is the following (15) to (22).
  • the step of preparing the coating material for the coating film of the uppermost layer includes a kneading step of kneading the solid content and the pinda solution, a dispersing step of dispersing the solid content in the kneaded material obtained in the kneading step, and a dispersing step.
  • the 95% cut filtration accuracy of the final filtration means in the binder solution filtration step is 4. ⁇ or more, and the 95% cut filtration accuracy of the final filtration means in the viscosity adjustment liquid filtration step is 1. 0 Aim or more,
  • the 95% cut filtration accuracy of the final filtration means in the binder solution filtration step is 80 ⁇ or less, and the 95% cut filtration accuracy of the final filtration means in the viscosity adjustment liquid filtration step is A method for producing a magnetic recording medium that satisfies at least one of the following conditions.
  • the step of preparing the coating material for the uppermost coating film reduces the amount of the kneaded material. At least one of a filtration step of the kneaded material to be filtered by at least one filtration means and a filtration step of the dispersion to be filtered by at least one filtration means,
  • the 95% cut filtration accuracy is at least 15 m in all cases, and the 95% cut filtration accuracy of the final filtration means in at least one of the kneaded material filtration process and the dispersion material filtration process is 80 m or less. 15) A method for manufacturing a magnetic recording medium.
  • the magnetic recording medium has at least two coating films on at least one surface of the nonmagnetic support, and the uppermost coating film has a magnetic thickness of 0.1 to 0.8 m.
  • the step of preparing the paint for the uppermost coating film includes a paint filtration step in which the paint is filtered by at least one filtration means, and a 95% cut filtration accuracy of the final filtration means in the paint filtration step. , 1.0-6. ⁇ ⁇ above
  • the step of preparing the paint for the uppermost coating film includes a step of passing the paint through at least one filtration means, and a step of 95% of the final passing means in the paint passing step.
  • the cut ripple accuracy is 10 times or less of the shortest recording wavelength, 6.0 m or less, and 1.0 Aim or more.
  • a magnetic layer is formed on the surface of the nonmagnetic support, a park coat layer formed by coating is formed on the back surface of the nonmagnetic support, and the thickness of the back coat layer is 1.0 m or less.
  • a method for producing a magnetic recording medium comprising: a step of preparing a coating material for a back coat layer; a step of dispersing a solid content in a binder solution; and a step of adding a viscosity adjusting liquid to the dispersion obtained in the dispersion step.
  • a viscosity adjusting step of obtaining a coating material further comprising: At least one of a filtration step of a Pinda solution that is filtered by at least one filtration means and a filtration step of a viscosity adjustment liquid that is filtered by at least one filtration means.
  • the 95% cut filtration accuracy of the final filtration means in the binder solution filtration step is 4.O / xm or more, and the 95% cut filtration accuracy of the final filtration means in the viscosity adjustment liquid filtration step is 1.0 m or more,
  • the 95% filter filtration accuracy of the final filtration means in the filtration step of the binder solution is 80 m or less, and the 95% cutoff of the final filtration means in the filtration step of the viscosity adjusting liquid.
  • a method for producing a magnetic recording medium that satisfies at least one of the following conditions: a precision of 30 m or less;
  • the step of preparing the coating material for the back coat layer includes a step of filtering the dispersion that has passed through the dispersion by at least one filtration means, and a final filtration in the step of filtering the dispersion.
  • the step of preparing the paint for the back coat layer includes a step of passing the paint through at least one filtering means, and 95% of the final filtering means in the passing step of the paint.
  • Embodiment 6 is the following (23) to (26).
  • a magnetic recording medium having at least two coating films on at least one surface of a non-magnetic support, wherein the uppermost coating film is a magnetic layer having a thickness of 0.1 to 0.8 ⁇ .
  • a method of manufacturing, At least the step of preparing the paint for the coating film adjacent to the uppermost layer includes a paint passing step of filtering the paint by at least one filtering means. % A method for manufacturing a magnetic recording medium having a cut accuracy of 1.0 to 6.0.
  • At least a step of preparing a paint for a coating film adjacent to the uppermost layer includes a kneading step of kneading a solid content and a binder solution, and a dispersing step of dispersing a solid content in a kneaded material obtained by the kneading step.
  • the step of preparing the paint for the uppermost coating film includes a step of filtering the paint through which the paint is passed by at least one filtering means.
  • the step of preparing the coating material for the uppermost coating film includes a kneading step of kneading the solid content and the pinda solution, a dispersing step of dispersing the solid content in the kneaded material obtained by the kneading step, and (25) The method for producing a magnetic recording medium according to the above (25), further comprising a viscosity adjusting step of adding a viscosity adjusting liquid to the dispersion obtained in the dispersion step to obtain a coating material.
  • Embodiment 7 is the following (27) to (28).
  • the magnetic recording medium has a back coat layer formed by coating on the back surface of the non-magnetic support, and the thickness of the back coat layer is 1. ⁇ or less,
  • the step of preparing the paint for the back coat layer includes a paint filtration step of filtering the paint by at least one filtration means, and the 95% cut accuracy of the final filtration means in the paint filtration step is 1. (23) to above, which is not less than 0 m and not more than 6.0 urn and not more than 10 times the thickness of the back coat layer. (26) The method for manufacturing a magnetic recording medium according to any of (26).
  • the step of preparing a paint for the back coat layer includes a dispersion step of dispersing solids in a binder solution, and a viscosity adjustment step of adding a viscosity adjusting liquid to the dispersion obtained in the dispersion step to obtain a paint.
  • Embodiment 8 is the following (29) to (31).
  • At least a step of preparing a paint for a coating film adjacent to the uppermost layer includes a kneading step of kneading a solid content and a binder solution, and dispersing a solid content in the kneaded material obtained by the kneading step.
  • the kneaded substance is filtered by at least one filtration means. At least one of a dispersion step and a dispersion step of passing the dispersion through at least one ruling means,
  • the 95% cut accuracy of the final filtration means in the kneaded material filtration step and the dispersion ripening step is both 15 urn or more, and the number of kneaded material filtration steps and dispersion filtration steps is small.
  • the step of preparing the coating material for the uppermost coating film includes a kneading step of kneading the solid content and the binder solution, a dispersing step of dispersing the solid content in the kneaded material obtained in the kneading step, and A viscosity adjusting step of adding a viscosity adjusting liquid to the dispersion obtained in the dispersion step to obtain a coating material; and further comprising a step of filtering the kneaded material which is filtered by at least one filtration means.
  • At least one of a dispersion filtration step of filtering the dispersion by at least one filtration means, and a paint filtration step of filtering the paint by at least one filtration means The 95% cut filtration accuracy of the final filtration means in the kneaded material filtration step and dispersion filtration step is 15 m or more, and at least the kneaded material filtration step and dispersion filtration step On the other hand, the 95% cut accuracy of the final filtration means is 80 ⁇ or less,
  • the magnetic recording medium has a back coat layer formed by coating on the back surface of the non-magnetic support, and the thickness of the back coat layer is 1. ⁇ or less,
  • the step of preparing the paint for the back coat layer includes a dispersion step of dispersing solids in a binder solution, and a viscosity adjustment step of adding a viscosity adjusting liquid to the dispersion obtained in the dispersion step to obtain a paint, A filtration step of filtering the dispersion by at least one filtration means; and a filtration step of a paint for filtering the coating material by at least one filtration means,
  • the 95% cut filtration accuracy of the final filtration means in the dispersion filtration step is 15 to 80 Mm, and the 95% cut filtration accuracy of the final filtration means in the paint filtration step is 1.0 m.
  • Embodiment 9 is the following (32) to (34).
  • At least a step of preparing a paint for a coating film adjacent to the uppermost layer includes a kneading step of kneading the solid content and the pinda solution, and a dispersing step of dispersing the solid content in the kneaded material obtained by the kneading step. And a viscosity adjusting step of adding a viscosity adjusting liquid to the dispersion obtained by the dispersing step to obtain a coating material. Further, the binder solution is filtered by at least one filtering means.
  • At least one of a binder solution passing step and a viscosity adjusting liquid filtering step of filtering the viscosity adjusting liquid by at least one damping means is provided, and the 95% cut of the final filtering means in the binder solution passing step is provided.
  • the filtration accuracy is more than 4. 4. ⁇
  • the 95% cut filtration accuracy of the final filtration means in the filtration process of the viscosity adjusting liquid is more than 1.0 m.
  • the 95% cut filtration accuracy of the final filtration means in the pinda solution filtration step is 80 ⁇ or less
  • the 95% cut filtration accuracy of the final filtration means in the viscosity adjustment liquid filtration step is The method for producing a magnetic recording medium according to any one of the above (23) to (31), which satisfies at least one of the conditions of 30 / zm or less.
  • the step of preparing the coating material for the coating film of the uppermost layer includes a kneading step of kneading the solid content and the pinda solution, a dispersing step of dispersing the solid content in the kneaded material obtained by the kneading step, and A viscosity adjusting step of adding a viscosity adjusting liquid to the dispersion obtained in the dispersing step to obtain a coating, further comprising a binder solution filtering step of filtering the binder solution by at least one filtration means; At least one of a viscosity adjusting liquid filtering step of filtering the viscosity adjusting liquid by at least one filtering means, and a paint filtering step of filtering the coating material by at least one filtering means,
  • the 95% cut filtration accuracy of the final filtration means in the binder solution filtration step is 4. ⁇ or more, and the 95% cut filtration accuracy of the final filtration step in the viscosity adjustment liquid filtration step is 1. 0 Aim or more,
  • the 95% cut filtration accuracy of the final filtration means in the binder solution filtration step is 80 m or less, and the 95% cut filtration accuracy of the final filtration means in the viscosity adjustment liquid filtration step is 30 urn or less. Satisfies at least one condition of
  • the 95% cut filtration accuracy of the final filtration means in the paint filtration process 1.
  • the magnetic recording medium has a back coat layer formed by coating on the back surface of the non-magnetic support, and the thickness of the back coat layer is 1.O Atm or less,
  • the step of preparing the paint for the back coat layer includes a dispersion step of dispersing a solid content in a binder solution, and a viscosity adjustment step of adding a viscosity adjusting liquid to the dispersion obtained in the dispersion step to obtain a paint.
  • a step of filtering the binder solution in which the binder solution is filtered by at least one damping means, and a step of filtering the viscosity adjusting liquid, in which the viscosity adjusting liquid is filtered by at least one filtering means.
  • a paint filtration step of filtering the paint with at least one filtration means
  • the 95% cut filtration accuracy of the final filtration means in the composting step of the binder solution is 4.O Atm or more, and the 95% cut filtration accuracy of the final filtration means in the viscosity adjustment liquid filtration step is Is greater than or equal to 1. ⁇ ⁇ ,
  • the 95% cut filtration accuracy of the final filtration means in the binder solution filtration step is 80 urn or less, and the 95% cut filtration accuracy of the final filtration means in the viscosity adjustment liquid filtration step is 30 urn. At least one of the following conditions:
  • At least one filtration step at least two filtration means are provided in series in the flow path of the material to be treated, and a 95% cut accuracy is provided upstream of the final filtration means.
  • Filter means larger than the final ripple means The method for manufacturing a magnetic recording medium according to any one of the above (1) to (34), wherein
  • the filtering means is a parallel filtering means having at least two filters having the same 95% cut-off accuracy and arranged in parallel in the flow path of the material to be processed.
  • the present invention is applied to the production of a single-layer magnetic recording medium or a multilayer magnetic recording medium having at least one coating film including a magnetic layer on at least one surface of a nonmagnetic support. At least the top layer of the coating is a magnetic layer.
  • the present invention is also applicable to the manufacture of a magnetic recording medium in which a back coat layer is provided by coating on the back surface of a non-magnetic support.
  • the magnetic layer on the surface of the non-magnetic support is not particularly limited, but when a coating type magnetic layer is provided, it is preferable to apply the present invention also to the formation of this magnetic layer.
  • a coating material for forming a coating film on the surface of the nonmagnetic support is generally prepared by the steps shown in the flowchart on the left side of FIG. 1. At least one is selected and installed as needed.
  • the paint for forming the pack coat layer is generally prepared by the steps shown on the right side of FIG. 1, but at least one of Steps VI to IX is selected as necessary in each embodiment of the present invention.
  • a final filtration means having a predetermined range of pore size (in the present invention, the pore size is defined as 95% cut filtration accuracy) is used.
  • final filtration means means a filtration means when a single filtration means is used in the filtration step, and a 95% cut filtration means when a plurality of filtration means are used. Means the filtration means with the lowest accuracy.
  • the contaminants in the pinner solution and the viscosity adjusting solution, gelled binders, undissolved binders, and the like, are subjected to the final filtration. It is captured accurately by means. For this reason, in the paint finally obtained, the deterioration of the medium characteristics caused by the inclusion of the above-mentioned trapping object and the presence of foreign matter in the coating film is prevented, and in particular, the drop rate is significantly reduced. I do. In addition, the properties of the coating film are improved, and the durability is improved.
  • the filtration V step for filtering paint In the filtration V step for filtering paint, the filtration II step for filtering the kneaded material, and the filtration III step for filtering the dispersion, non-dispersed substances such as magnetic powders and non-magnetic powders, re-agglomerated substances, An object to be captured is accurately captured by the final filtration unit. Therefore, the dropout of the manufactured magnetic recording medium is significantly reduced.
  • the final filtration means used in these filtration steps does not unnecessarily filter abrasive particles added for improving the durability of the magnetic coating film, a coating film having excellent durability can be obtained. can get.
  • the final filtration means used in the filtration step VI for filtering the pinda solution and the filtration step VIII for filtering the viscosity adjusting solution are the same as those used in the filtration step I and the filtration step IV, respectively. It shows a similar effect.
  • step IX which filters the paint
  • step VII in which the dispersion is filtered, the resin insolubles, undispersed or re-agglomerated materials such as conductive pigments and various abrasives that are often added, and An object to be captured such as a solid impurity mixed in the manufacturing process is accurately captured by the final filtration unit. Therefore, the dropout of the manufactured magnetic recording medium is significantly reduced.
  • the final filtration method used in the filtration IX step and the filtration VII step requires excessive amounts of abrasive particles added to improve the durability of the back coat layer and conductive pigments for preventing static electricity. I can't filter it. Therefore, a back coat layer having excellent durability and a high antistatic effect can be obtained. It is also known that carbon black used in the back coat layer has extremely poor dispersibility. However, when filtration is performed by such a filtration means, a strong shearing force is applied to the paint and the dispersion, so that a ball mill is used. The dispersibility is significantly improved as compared with the case where only the conventional dispersing process using the above method is used. For this reason, the dropout of the magnetic recording medium is further reduced.
  • the dropout After a magnetic recording medium is stored under severe conditions such as high temperature and high humidity, the dropout generally increases significantly and the electromagnetic conversion characteristics deteriorate.
  • the uppermost magnetic layer is as thin as 0.1 to 0.8 / xm in a magnetic recording medium having a multi-layer coating film, the influence of foreign matter in the coating film adjacent to the uppermost layer is large. As a result, the dropout increases and the electromagnetic conversion characteristics tend to decrease.
  • Embodiments 6 to 9 in the filtration step when preparing a paint for a coating film adjacent to the uppermost layer, by using the above-mentioned final damping means, after storing under high-temperature and high-humidity conditions, However, an increase in drop weight and a decrease in electromagnetic characteristics are hardly recognized.
  • a plurality of fluids to be filtered are stored in series in a flow path 202 connected to a tank 201 in which a plurality of fluids are stored.
  • a filter filter F
  • a ripple means having a larger diameter than the final filtration means is disposed.
  • the large filtering means having a large pore diameter upstream of the flow path captures a coarse capturing target in the material to be filtered, and passes a small capturing target.
  • the final filtration means downstream of the flow path captures the minute capture target that has passed through the ripple means upstream of the flow path.
  • a parallel filtration means 203 in which two or more filters F are arranged in parallel with the flow path 202.
  • the filtration area is reduced.
  • increase the diameter of the base material or increase the axial length it is difficult to reduce the variation in the pore size with a large-diameter filter medium, which causes a problem in filtration accuracy.
  • the parallel filtration means of the present invention uses a plurality of filter media having a relatively small diameter and a relatively short axial length, so that a large filtration area can be obtained, and high-precision filtration is possible, and the service life is long Is also longer.
  • the material to be filtered in the tank 201 is circulated through a filtering means (filter F).
  • the kneaded material or dispersion may have a longer residence time in the tank 201.
  • paint that has passed through the filtration V step and the filtration IX step is usually supplied with a curing agent and supplied to the coating step. The residence time of the paint may increase. Fine particles in kneaded materials, dispersions, and coatings tend to agglomerate, and in particular, magnetic particles having high coercive force and high saturation magnetic flux density tend to agglomerate. Agglomerates tend to form.
  • FIG. 1 is a flowchart showing a process of preparing a coating material for a magnetic layer, a coating material for a non-magnetic layer, and a coating material for a backcoat layer.
  • FIG. 2 are partial cross-sectional views showing a configuration example of a magnetic recording medium manufactured according to the present invention.
  • FIG. 3 is a schematic configuration diagram of an apparatus used for a method for obtaining a 95% cut filtration accuracy of a filter.
  • 4 to 11 are schematic diagrams each showing a filter arrangement in a filtration step.
  • Embodiments 2 to 5 of the present invention include a method for producing a magnetic recording medium having a single magnetic layer on at least one surface of a nonmagnetic support.
  • FIG. 2 (a) shows a configuration example of such a magnetic recording medium.
  • the magnetic layer 3 is provided on the surface of the non-magnetic support 2
  • the back coat layer 4 is provided on the back side of the non-magnetic support.
  • the back coat layer 4 is provided as needed.
  • the magnetic recording medium (multi-layer medium) having at least two coating films on at least one surface of the non-magnetic support, and at least the uppermost coating film is a magnetic layer.
  • Embodiments 1 and 3 to 9 include a method for producing a magnetic recording medium which is such a multilayer medium, wherein the uppermost coating film is a magnetic layer having a thickness of 0.1 to 0.8 ⁇ . .
  • FIG. 2 (b) shows a configuration example of such a magnetic recording medium.
  • a lower layer 5 and an upper layer 6 are provided in this order on the surface of the non-magnetic support 2, and on the back side of the non-magnetic support.
  • the back coat layer 4 is provided.
  • the back coat layer 4 is provided as needed.
  • the lower layer 5 is a non-magnetic layer or a magnetic layer
  • the upper layer 6 is a magnetic layer.
  • the multilayer medium produced by the present invention may have three or more coating films on the surface of the non-magnetic support.
  • all coatings may be magnetic layers, and coatings other than the uppermost layer may be nonmagnetic layers.
  • coatings other than the uppermost layer may be nonmagnetic layers.
  • a nonmagnetic layer usually only the lowermost layer is nonmagnetic.
  • Magnetic layer usually only the lowermost layer is nonmagnetic.
  • Embodiments 3 to 5 and 7 to 9 of the present invention each have a magnetic layer having a magnetic layer on the surface of a nonmagnetic support and a backcoat layer on the backside, wherein the thickness of the backcoat layer is 1.0 m or less.
  • the magnetic layer is not particularly limited, and may be, for example, a coating type or a continuous thin film type.
  • Non-magnetic supports include polyethylene esters such as polyethylene terephthalate (PET) and polyethylene terephthalate (PEN); polyolefins; Among these, PET, PEN, and aromatic boride are preferable, and a composite film obtained by multi-layer coextrusion of two or three kinds of PET or PEN is particularly preferable. The use of these films improves the balance between electromagnetic characteristics, durability, friction characteristics, film strength, and productivity.
  • PET polyethylene esters
  • PEN polyethylene terephthalate
  • PEN polyethylene terephthalate
  • aromatic boride are preferable, and a composite film obtained by multi-layer coextrusion of two or three kinds of PET or PEN is particularly preferable. The use of these films improves the balance between electromagnetic characteristics, durability, friction characteristics, film strength, and productivity.
  • the nonmagnetic support may contain, as fillers, inorganic compounds such as oxides and carbonates such as A1, Ca, Si, and Ti, and organic compounds such as acrylic resin-based fine powder.
  • inorganic compounds such as oxides and carbonates such as A1, Ca, Si, and Ti
  • organic compounds such as acrylic resin-based fine powder.
  • the surface properties are automatically controlled by these amounts and sizes. Control, and as a result, it becomes possible to control electromagnetic characteristics, durability, friction characteristics, and the like.
  • non-magnetic supports may be previously subjected to corona discharge treatment, plasma discharge and Z or polymerization treatment, easy adhesive application treatment, dust removal treatment, relaxation treatment by heat and / or humidity control, and the like.
  • the surface roughness of the nonmagnetic support is preferably not more than 0.03 wm, more preferably not more than 0.02 ⁇ , further preferably not more than 0.01 ⁇ , in terms of center line average roughness Ra. It is preferable that not only the surface roughness is small but also that there are no coarse protrusions of 0.5 ⁇ or more.
  • the heat shrinkage of the nonmagnetic support in the longitudinal and width directions at 100 and 30 minutes is preferably 3% or less, more preferably 1.5% or less, and is 80 * C ⁇ 30 minutes.
  • the thickness of the nonmagnetic support is preferably from 4.0 to 75.0. If it is too thin, the mechanical strength of the magnetic recording medium cannot be maintained, and the durability will be reduced. If the thickness is too large, the total thickness of the magnetic recording medium becomes too large, and the recording amount per unit volume decreases, which is not preferable.
  • This magnetic layer contains at least a magnetic powder and a pinda.
  • iron oxide magnetic powder for example, those shown below are preferably used.
  • the iron oxide magnetic powder used in the present invention ⁇ _ ⁇ F e 2 0 a, F e 3 ⁇ , ⁇ - F e 2 0 3 and a solid solution of F e 3 C, C o compound-coated ⁇ - F e 2 03, C o compound Dove type ⁇ one F e 2 0 3, C o compound-coated F e 3 04, C o compound Dove type F e 3 0,, C o compound-coated r-Fe 2 O a and Co compound-coated F e 3 0, a solid solution of a solid solution such as the Co compound Dove type ⁇ one Fe 2 0 3 and Co compounds Dove type F e 3 0. thereof.
  • the Co compound means a compound that utilizes the magnetic anisotropy of the copart to improve the coercive force, such as cobalt oxide, cobalt hydroxide, cobalt fluoride, and cobalt ion adsorbate.
  • the ratio of trivalent iron divalent iron in the case where C o is used ⁇ _ ⁇ F e 2 0 3 that is deposited or dove is preferably from 0 to 20%, more preferably at 2-10% is there.
  • the ferromagnetic metal powder used in the present invention examples include ferromagnetic metal elements such as ⁇ -Fe, Fe—Co, Fe—Ni, Fe—Co—Ni, Co, and Co—Ni.
  • the main component is exemplified.
  • the ferromagnetic metal (Fe, Co, Ni, etc.) or alloy is preferably contained in an amount of 70% by weight or more, more preferably 75% by weight or more.
  • the ratio of Co atoms to Fe atoms is preferably 0 to 40 mol%, more preferably 6 to 35%.
  • the ferromagnetic metal powder containing Fe and / or Co as a main component further contains at least one rare earth element containing Y.
  • these ferromagnetic metal powders may have an oxide film on the particle surface, a partially carbonized or nitrided surface, or a carbonaceous film formed on the surface.
  • the ferromagnetic metal powder may contain a small amount of hydroxide or oxide.
  • These ferromagnetic metal powders may be manufactured based on a known method.
  • Examples of the production method include a method in which an organic acid salt of a ferromagnetic metal (mainly oxalate) is reduced with a reducing gas such as hydrogen, a hydrous iron oxide or a hydrous acid.
  • a method of returning iron oxide obtained by heating iron oxide with a reducing gas such as hydrogen, a method of thermally decomposing a metal carbonyl compound, a method of dissolving sodium borohydride and hypophosphorous acid in an aqueous solution of a ferromagnetic alloy examples thereof include a method of adding a reducing agent such as a salt and hydrazine to reduce, and a method of evaporating a metal in a low-pressure inert gas to obtain a fine powder. Further, the ferromagnetic metal powder obtained in this manner may be subjected to a known slow oxidation treatment.
  • the method of gradual oxidation treatment is a method of immersing in an organic solvent and then drying, a method of immersing in an organic solvent and then sending an oxygen-containing gas to form an oxide film on the surface and drying, and using no organic solvent
  • a method of adjusting the partial pressure of the oxygen gas and the inert gas to form an oxide film on the surface is exemplified.
  • the present invention can also be used acicular Cr0 2 magnetic powder.
  • a magnetic powder having a hexagonal plate shape and an axis of easy magnetization perpendicular to the plate surface for example, a plate-like hexagonal ferrite may be used.
  • magnetic powders include Ba—Frite, Sr—Ferrite, Pb—Ferrite, C—Frite, and metal atom-substituted ferrite that combines the valences of these Fe atoms. Is mentioned.
  • the magnet blank type Ba-ferrite and Sr-ferrite, and the magnet blank type Ba-ferrite and Sr-ferrite containing a part of viner phase Particularly preferred are metal atom-substituted filaments in which the valences of Fe atoms are matched to control the coercive force of Ba-ferrite or Sr-ferrite.
  • the metal atoms used to control the coercive force are Co—Ti, Co—Ti—Sn, Co—Ti—Zr, Cu—Zn, Cu—Ti—Zn, and! ⁇ ! ! It is preferable to use such as.
  • the average plate diameter is It is preferable that the thickness is 0.01 to 0.1 m and the average thickness is 1 Z2 to 1 ⁇ 20.
  • the plate diameter of the hexagonal plate-shaped magnetic powder means the diameter of the hexagonal plate, which is measured using an electron microscope.
  • All the magnetic powders described above are Al, Si, Cr, Mn, Co, Ni, Zn, Cu, Zr, Ti, Bi, Ag, Pt, B, C, P, N, Y, S, Sc, V, Mo, Rh, Pd, Ag, Sn, Sb, Te, Ba, Ta, W, Re, Au, H
  • a small amount of elements such as g, Pb, La, Sr, and rare earth elements may be added.
  • the addition of at least one of Al, S i> P and rare earth elements (including Y) has the effects of improving the particle size distribution and preventing sintering.
  • a ferromagnetic metal powder it may contain inorganic ions such as water-soluble Na, K, Ca, Fe, and Ni, but the amount is preferably 500 ppm or less, more preferably 30 ppm or less. Oppm or less.
  • These magnetic powders may be previously treated with a dispersant, a lubricant, a surfactant, an antistatic agent or the like before dispersion.
  • the water content of the magnetic powder may be 0.1 to 2%, but is preferably optimized according to the type of the binder.
  • the PH of the magnetic powder is preferably optimized according to the combination with the binder used, and the range is preferably from 4 to 12, more preferably from 6 to 10.
  • the specific surface area of these magnetic powders by the BET method is preferably from 25 to 80 m 2 / g, more preferably from 40 to 7 OmVg. Specific surface area is too small If it is too large, the noise will be high. If it is too large, good surface properties will not be obtained, which is not preferable.
  • the content of the magnetic powder with respect to the binder is usually about 100 to 200 parts by weight with respect to 100 parts by weight of the binder, and the content of the magnetic powder in the entire magnetic layer is It is preferably from 50 to 95% by weight, more preferably from 55 to 90% by weight. If the content of the magnetic powder in the magnetic layer is too large, the amount of additives such as resin in the magnetic layer becomes relatively small, so that defects such as a decrease in durability of the magnetic layer are likely to occur. On the other hand, if the amount is too small, it is difficult to obtain a high reproduction output.
  • the above magnetic powders may be used alone or in combination of two or more.
  • the coercive force H c of the magnetic powder is usually selected between 200 and 300 Oe based on the system requirements, but in general, if He is too large, the normal Recording and erasing of signals at the head becomes difficult, while if too small, sufficient reproduction output cannot be obtained in short-wavelength recording.
  • Hc in the ferromagnetic metal powder is preferably from 110 to 250 Oe, more preferably from 140 to 200 Oe, and particularly the shortest recording wavelength is 1 m or less. For short-wavelength recording, Hc of 150 Oe or more is preferable.
  • the saturation magnetization (os) may be selected as appropriate, but if the os is low, a high reproduction output cannot be obtained, so an experiment is performed to obtain the highest possible saturation magnetization while considering physical properties such as durability and friction. Is preferably selected.
  • the shape of these magnetic powders is needle-like, spindle-like, granular, spherical, plate-like, etc., and an appropriate shape may be selected according to the use of the magnetic recording medium. It is preferable to use needle-shaped or spindle-shaped ones rather than spherical or granular ones, because the effect of orientation treatment can be expected to be higher, and the effect of increasing the strength of the magnetic layer in the longitudinal direction can be expected. Good.
  • the axis ratio (major axis / minor axis) of the needle-shaped or spindle-shaped magnetic powder is not particularly limited, but usually the above-mentioned effects can be sufficiently expected if the axis ratio is about 3 to 10.
  • the ferromagnetic metal powder generally has a needle shape
  • the needle shape in the present invention refers to a material in which the long axis end of the ferromagnetic metal powder is relatively sharp (this is generally a spindle.
  • This is a broad concept that includes from the shape of the shape to the hemisphere or near flat. More specifically, it is a shape formed by rotating X and Y satisfying the following expression around the X axis.
  • n can take a value of 1 ⁇ ⁇ 100, preferably 1.2. ⁇ n ⁇ 20, more preferably 1.5 ⁇ n ⁇ 10.
  • k represents a so-called axial ratio, that is, a ratio of a major axis length / a minor axis diameter.
  • the average particle size of the magnetic powder may be about 0.05 to 0.8 m, but in the case of a needle or spindle, preferably the average major axis is 0.05 to 0.3 izm and the average axial ratio is 3 And more preferably about 0.08 to 0.2 ⁇ and an average axial ratio of 5 to 8. If the average major axis is too large, the bulk noise of the tape increases, while if the average major axis is too small, aggregation of the magnetic powder in the magnetic paint tends to occur.
  • thermoplastic resin a thermoplastic resin, a thermosetting or reactive resin, an electron beam-sensitive modified resin, or a mixture thereof is used, and a combination thereof may be appropriately selected according to the characteristics of the medium, process conditions, and the like.
  • the thermoplastic resin preferably has a softening temperature of 150 * 1 or less, an average molecular weight of about 5,000 to 200,000, and a degree of polymerization of about 50 to 2,000.
  • Thermosetting or reactive resins and electron beam functionalized modified resins have the same average molecular weight and polymerization as thermoplastic resins. It is preferable that the molecular weight be infinite by a reaction such as condensation or addition by heating and / or electron beam irradiation after coating, drying and calendering.
  • thermoplastic resin examples include a combination of a vinyl chloride copolymer and a polyurethane resin as shown below.
  • a thermoplastic resin will be described as an example.
  • the butyl chloride copolymer preferably has a butyl chloride content of 60 to 95% by weight, particularly 60 to 90% by weight, and has an average degree of polymerization of about 100 to 500. Is preferred.
  • butyl chloride copolymer examples include butyl chloride monoacetate butyl alcohol copolymer, butyl chloride monohydroxyalkyl (meth) acrylate copolymer, vinyl chloride-butyl acetate maleic acid, and chloride.
  • such a chlorinated vinyl copolymer includes a sulfate group and Z or the like.
  • a compound containing a sulfo group as a polar group (hereinafter referred to as an S-containing polar group) is preferred.
  • S-containing polar group an S 0 4 Y, - S 03 Y
  • either one of these S-containing polar groups may be contained, or both may be contained. When both are contained, the ratio is arbitrary.
  • These S-containing polar groups are preferably contained in the molecule in an amount of 0.01 to 10% by weight, particularly 0.1 to 5% by weight in terms of S atoms.
  • the polar group in addition to the S-containing polar group, optionally one 0 ⁇ 0 2 ⁇ group one .rho.0 3 Upsilon group one COOY group (Upsilon is Eta, alkali metal), Amino group (one NR 2), -NR 3 CI (R is H, methyl group, ethyl group) and the like can be contained.
  • the amino group may not be used in combination with the above-mentioned S, and may be of various types, but is particularly preferably a dialkylamino group (preferably alkyl having 1 to 10 carbon atoms). Such an amino group is usually obtained by amine modification.
  • Bulk chloride alkyl force Disperse or dissolve rubonic acid butyl ester copolymer in an organic solvent such as alcohol, and dissolve amine compound (aliphatic amine, alicyclic amine, alkanolamine, alkoxyalkylamine, etc.) Primary, secondary or tertiary amines) and an epoxy group-containing compound for facilitating the saponification reaction and then performing the saponification reaction.
  • the number of the bullet units having an amino group is preferably 0.05 to 5% by weight. Note that an ammonium base may be included as a result.
  • the resin skeleton to which the S-containing polar group is bonded is a vinyl chloride resin, and is used to convert perchloric acid to a monomer having a butyl chloride, an epoxy group-containing monomer, and, if necessary, a copolymerizable with them. It can be obtained by polymerization in the presence of a radical generator having a strong acid radical containing S, such as potassium or ammonium persulfate. You.
  • the amount of these radical generators used is usually from 0.3 to 9.0% by weight, preferably from 1.0 to 5.0% by weight, based on the monomer.
  • radical generator having a strong acid radical containing S it is also possible to use a radical generator used for normal polymerization of vinyl chloride. It is also possible to combine a radical generator having a strong acid radical containing S with a reducing agent such as sodium formaldehyde sulfoxylate, sodium sulfite or sodium thiosulfate.
  • Examples of monomers having an epoxy group include glycidyl ethers of unsaturated alcohols such as (meth) aryl glycidyl ether, and glycidyl.
  • Glycidyl esters of (meth) acrylic acid such as (meth) acrylate, glycidyl p-bulbenzoate, methyl glycidyl nitrate, glycidyl ethyl malate, glycidyl vinyl sulfonate, glycidyl (meth) aryl sulfonate, etc.
  • Glycidyl esters of unsaturated acids butadiene monooxide, butylcyclohexene monooxide, epoxide olefins such as 2-methyl-5,6-epoxyhexene, etc. It is used in a range where the amount of the epoxy group is 0.5% by weight or more.
  • Examples of monomers that can be used as needed in addition to the monomer having a butyl chloride and an epoxy group include carboxylic acid butyl esters such as butyl acetate and butyl propionate, methyl butyl ether, and isobutyl vinyl ether.
  • Butyl ether such as cetyl butyl ether; vinylidene chloride such as vinylidene chloride; vinylidene fluoride; getyl maleate; butyl benzyl maleate; di-2-hydroxyethyl maleate; dimethyl itaconate; methyl (meth) acrylate; Meta) ethyl acrylate, Unsaturated carboxylate esters such as (meth) lauryl acrylate, (meth) acrylic acid 2-hydroxypropyl pyrrole and the like; olefins such as ethylene and propylene; and unsaturated nitriles such as (meth) acrylonitrile. It is possible.
  • Polyurethane resins used in combination with vinyl chloride resins are particularly effective in that they have good abrasion resistance and good adhesion to the support, even those having polar groups, hydroxyl groups, etc. in the side chains. Of these, those containing a polar group containing sulfur S or phosphorus P are particularly preferred.
  • Such a polyurethane resin is a general term for resins obtained by reacting a hydroxy group-containing resin such as a polyester polyol and a poly or polyether polyol with a polyisocyanate-containing compound, and will be described in detail below.
  • the synthetic raw material is polymerized to a number average molecular weight of about 500 to 200,000, and its Q value (weight average molecular weight Z number average molecular weight) is about 1.5 to 4.
  • M, M 1 , and M 2 represent H, Li, Na, K, - ⁇ R 3 , - ⁇ ⁇ R 2 , R represents an alkyl group or ⁇ , and X represents a halogen atom.
  • ⁇ is particularly preferably Na. It is preferable to use one obtained by introducing at least one polar group selected from these polar groups by copolymerization or addition reaction. These polar groups are separated as atoms. It is preferable that the content is 0.01 to 10% by weight, particularly 0.02 to 3% by weight in the child. These polar groups may be present in the main chain of the skeleton resin or in the branches.
  • the polyurethane resin used in the present invention has a glass transition temperature T g of ⁇ 20 ° C.
  • binders in the range of ⁇ s ⁇ 8 o e c and different in ⁇ g are contained in the binder. Further, the total amount is preferably 10 to 90% by weight of the total binder. It is preferable to include such a plurality of polyurethane resins in terms of running stability in a high temperature environment, calendar workability, and a balance of electromagnetic conversion characteristics.
  • Such a polyurethane resin is prepared by reacting a specific polar group-containing compound and / or a raw material containing a raw material resin or the like reacted with a specific polar group-containing compound in a solvent or without a solvent by a known method. can get.
  • the carboxylic acid component of the polyester diol which is a raw material, includes terephthalic acid, isophthalic acid, orthophthalic acid, aromatic dicarboxylic acids such as 1,5-naphthalic acid, P-oxybenzoic acid, and P- (hydroxyethoxy).
  • Aromatic carboxylic acids such as benzoic acid, succinic acid, adipic acid, azelaic acid, sebacic acid, aliphatic dicarboxylic acids such as dodecanedicarboxylic acid, fumaric acid, maleic acid, itaconic acid, and tetrahydrofuran Acids, unsaturated fatty acids such as hexahydrophthalic acid and the like, and tri- and tetracarboxylic acids such as alicyclic dicarboxylic acid, trimellitic acid, trimesic acid, and pyromellitic acid.Alcohol components include ethylene glycol.
  • polyester polyol examples include a lactone-based polyesterdiol chain obtained by ring-opening polymerization of a lactone such as force prolactone.
  • Polyisocyanates used include tolylene diisocyanate, phenylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, and tetramethylene diisocyanate.
  • Diisocyanates such as naphthalene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, diisocyanatomethylcyclohexane, diisocyanatocyclohexylmethane, dimethyloxybiphenylene diisocyanate, and diisocyanatodiphenyl ether.
  • trisocyanate compounds such as trimeric diisocyanate trimers and hexamethylene diisocyanate trimers of 7 mol% or less of all isocyanate groups.
  • the vinyl chloride-based copolymer and the S and z or P-containing polar group-containing polyurethane resin may be mixed and used in a weight mixing ratio of 10:90 to 90:10. preferable.
  • various kinds of public resins may be contained in a range of 20% by weight or less based on the whole.
  • thermoplastic resins are thermoplastic resins
  • thermoplastic resin other than the above examples include (meth) acrylic resin, polyester resin, acrylonitrile-butadiene copolymer, boriamid resin, polybutyral, nitrocellulose, styrene-butadiene copolymer, Polyfunctional alcohols, acetal resins, epoxy resins, polyoxy resins, polyether resins, polyfunctional polyethers such as polycaprolactone, polyamide resins, polyimide resins, phenol resins, polybutadiene elastomers, rubber chlorides , Acrylic rubber, isoprene rubber, and epoxy-modified rubber.
  • Thermosetting resin or reactive resin are Thermosetting resin or reactive resin
  • Thermosetting resins include polyunol resin, epoxy resin, polyurethane curable resin, urea resin, petital resin, bolimar resin, melanin resin, alkyd resin, silicone resin, acrylic-based reaction resin, and polyamide resin that undergo condensation polymerization. And epoxy-polyamide resins, saturated polyester resins, and urea-formaldehyde resins.
  • those having a hydroxyl group at a terminal and / or a side chain are preferable because a reactive resin such as crosslinking using isocyanate or electron beam crosslinking can be easily used.
  • a reactive resin such as crosslinking using isocyanate or electron beam crosslinking can be easily used.
  • one COOH as - S 0 a M, - 0 S 0 3 M, - 0 P 0 3 X, one P 0 3 X, one P 0 2 X, -NR 3 C l, - including NR 2, etc. It may contain an acidic polar group, a basic polar group, etc. Suitable. M and X have the same meanings as described above. These may be used alone or in combination of two or more.
  • crosslinking agent for curing such a binder resin various polyisocyanates can be used, and at least one of tolylene diisocyanate, hexamethylene diisocyanate, methylene diisocyanate, and the like, It is preferable to use a cross-linking agent modified to one having a plurality of hydroxyl groups such as trimethylolpropane or an isocyanurate-type cross-linking agent in which three molecules of a diisocyanate compound are bonded.
  • the content of the cross-linking agent is 100 parts by weight of the resin. The amount is preferably from 10 to 30 parts by weight, and the crosslinking agent three-dimensionally bonds the binder resin and the hydroxyl group contained therein, thereby improving the durability of the coating film layer.
  • Coronate L, HL, 3041 manufactured by Nippon Polyurethane Industry Co., Ltd., 24A—100
  • TPI-100 manufactured by Asahi Kasei Kogyo Co., Ltd., manufactured by B.F. Desmodules L, N, etc. are used.
  • the resin is generally heated in a heating oven at 50 to 80 for 6 to 100 hours, or an oven at 80 to 120 ° C. It only has to run at low speed inside.
  • the acrylic double bond as used herein means a (meth) acryloyl group which is a residue of (meth) acrylic acid, (meth) acrylic ester, and (meth) acrylic amide.
  • Methods of performing this electron beam sensitive denaturation include tolylene diisocyanate (TDI) and 2-hydroxyethyl (meth) acrylate (2-HE).
  • TDI tolylene diisocyanate
  • 2-HE 2-hydroxyethyl (meth) acrylate
  • MA ethylenically unsaturated double bonds and one isocyanate group in one molecule, and a urethane bond in the molecule.
  • An improved type in which a monomer having no (such as 2-isocyanatoethyl (meth) acrylate) is reacted with the resin.
  • the resin is modified with urethane, and the (meth) acrylic group and carboxylic anhydride or dicarboxylic acid are added to the
  • ester modification is carried out by reacting a compound having the same.
  • the improved urethane modification does not become brittle even when the content ratio of the vinyl chloride copolymer is increased, and furthermore, the dispersibility and It is preferable because a coating film having excellent surface properties can be obtained.
  • the content of the electron beam functional group is 1 to 40% by mole, preferably 10 to 30% by mole in the hydroxyl group component in view of the stability at the time of production, the electron beam curability, and the like.
  • an electron beam-curable resin having both excellent dispersibility and curability can be obtained by reacting a monomer so that the number of functional groups becomes 1 to 20 and preferably 2 to 10 per molecule. Can be.
  • conventionally known polyfunctional acrylates may be used in a mixture of 1 to 50% by weight in order to improve the crosslinking rate.
  • the method of using an electron beam as a radiation source for curing is from the viewpoint of controlling the absorbed dose, introducing it into the production process line, and shielding ionizing radiation.
  • a method using ultraviolet light or ultraviolet light is advantageous.
  • the electron beam crosslinking it is important that the oxygen concentration is irradiated with an electron beam with 1% or less of N 2, H e, an inert gas atmosphere of C 0 2 or the like.
  • UV light when ultraviolet light is used, a conventionally known photopolymerization sensitizer is added to a binder containing an electron beam-sensitive modified resin, and an ultraviolet light source such as a xenon discharge tube or a hydrogen discharge tube is used as an irradiation source. Etc. may be used.
  • non-magnetic powders are preferably contained in the magnetic layer in order to increase the mechanical strength of the magnetic layer and prevent clogging of the magnetic head.
  • the non-magnetic powder may be appropriately selected from the following non-magnetic inorganic powder and non-magnetic organic powder as needed.
  • the non-magnetic powder is used in the magnetic layer with respect to the magnetic powder.
  • Non-magnetic inorganic powders other than carbon black include, for example, metals, metal oxides, metal carbonates, metal sulfates, metal nitrides, metal carbides, metal sulfides, and the like. Specifically, alpha - alumina, 0 - alumina, ⁇ -alumina, e - alumina, .delta.-alumina trioxide nichrome, alpha-iron oxide, ⁇ over iron oxide, Getai DOO, S i 0 2, Z n O, T i 0 2, Z r 0 2, S n 0 2, silicon nitride, boron nitride, silicon carbide, titanium carbide, carbonitride, molybdenum, boron carbide, tungsten carbide, calcium carbonate, barium carbonate, strontium carbonate, magnesium carbonate, sulfate Barium, zinc sulfide, molybdenum disulfide, tungsten disulfide, artificial diamond
  • the nonmagnetic inorganic powder may be used in an appropriate combination according to the required characteristics of the magnetic layer, and the same applies to the case where the nonmagnetic inorganic powder is added to the backcoat layer, the underlayer, and the like.
  • the nonmagnetic inorganic powder may be a single type or a mixed type, and the particle size distribution or the like may be appropriately selected alone.
  • the shape, size, etc. of the particles of the non-magnetic inorganic powder depend on the durability required for the medium. It may be appropriately selected based on the head wear and the output balance at the shortest recording wavelength, etc., but the particle shape is preferably spherical or polyhedral, and the particle size is preferably 0.01 to 0.01. 7 m.
  • the non-magnetic inorganic powder need not be 100% pure, and the effect is not reduced if the main component is 70% or more.
  • Non-magnetic inorganic powders need to contain a small amount of water-soluble ions such as alkali metals, alkaline earth metals, chlorine, sulfuric acid, and nitric acid. Exert.
  • the nonmagnetic inorganic powder may be added at the same time as kneading or dispersing with the ferromagnetic powder, or may be previously dispersed in a pinda and added when dispersing the magnetic paint.
  • furnace carbon black thermal carbon black
  • acetylene black and the like can be used as the carbon black.
  • the particle size of the carbon black is appropriately selected in consideration of various characteristics required for the medium, for example, the balance between the friction characteristics and the output at the shortest recording wavelength (depending on the surface roughness), electric resistance, and the like. do it.
  • Carbon black may be used in an appropriate combination according to the required characteristics of the magnetic layer, and the same applies to the case where carbon black is added to the pack coat layer, the underlayer, and the like.
  • the carbon black may be a single type or a mixed type, and the particle size distribution and the like may be appropriately selected alone.
  • the average particle size of the carbon black is preferably from 10 nm to 40 O nm, and more preferably from 20 to 35 O nm.
  • the specific surface area (BET value) of the carbon black is preferably from 100 to 500 mVg, and more preferably from 150 to 400 m 2 / g, but the particle size, BET value and DBP of the carbon black are preferred. Since the oil absorption is closely related to each other, and it is practically impossible to make a value that is far apart by itself, these three factors are experimentally determined by the required characteristics of the medium and the dispersion characteristics and flow characteristics of the paint. It is necessary to select
  • Carbon black may be added at the same time as the ferromagnetic powder is kneaded, or may be previously dispersed in a binder and added at the time of dispersion of the magnetic paint.
  • Carbon black may be subjected to a surface treatment with a lubricant, a dispersant, or the like, or a carbon black obtained by partially graphitizing the surface.
  • Carbon Black Handbook (edited by Carbon Black Association).
  • Non-magnetic organic powders include acrylic styrene resin powder, benzoguanamine resin powder, melamine resin powder, phthalocyanine pigment, polyolefin resin powder, polyester resin powder, polyamide resin powder, polyimide resin Powder, fluorocarbon resin powder, divinylpentene resin powder and the like.
  • the coating material for forming the magnetic layer is prepared by adding an organic solvent to each of the above components.
  • an organic solvent used for preparing the coating material, and it may be appropriately selected in consideration of the solubility, compatibility, drying efficiency, etc. of the binder.
  • the solvent used for preparing the coating material may be appropriately selected in consideration of the solubility, compatibility, drying efficiency, etc. of the binder.
  • Ketones Aromatic hydrocarbons such as benzene and xylene, esters such as ethyl acetate and butyl acetate, alcohols such as isopropanol and butanol, dioxane, tetrahydrofuran, dimethylformamide, hexane, and chlorinated hydrocarbons It is preferable to use a diluent or a solvent such as a single solvent or a mixed solvent obtained by mixing these in an arbitrary ratio.
  • organic solvents do not need to be 100% pure and may contain impurities such as isomers, unreacted substances, by-products, decomposed products, oxides, and moisture in addition to the main components.
  • impurities are preferably at most 5% by weight, more preferably at most 3% by weight. A large amount of impurities adversely affects the dispersibility of the magnetic powder, the storage stability of the paint, the hardening properties of the magnetic layer, and the storage properties of the medium.
  • organic solvents are used so that the viscosity of the paint becomes 5 to 100 cp at a coating rate of 3,000 Osec " 1 using a cone-plate or double-cylindrical viscometer at the stage of application. It is preferable to use 100 to 100,000% by weight, particularly 100 to 5,000% by weight, based on the total amount.
  • the solvent may be used at a concentration of 5 to 45% by weight, preferably about 10 to 40% by weight.
  • the solvent type, the mixing ratio, and the amount used are determined based on the type and ratio of the pigment used in the paint.
  • the viscosity range is appropriately determined in consideration of the surface area, particle size, the amount of magnetization of the magnetic powder, the degree of filling of the pigment or volume, and the dilution stability of the paint. preferable.
  • the organic solvent addition operation is preferably performed step by step in each process of paint production, such as adding the solvent sequentially while stirring into the tank with flow rate regulation, or gradually mixing with the paint via piping. It is good to do. If possible, it is more preferable to carry out filtration and Z or dispersion treatment when adding or diluting a solvent. By performing these operations, the paint The stability is improved, and the generation of aggregates and foreign substances can be suppressed.
  • a dispersant, a lubricant, and other various additives may be added to the magnetic layer.
  • the lubricant used in the present invention it is preferable to use, among various known lubricants, particularly fatty acids and amino acids or fatty acid esters, and having 12 to 24 carbon atoms (including unsaturated bonds, Monobasic fatty acids) or monobasic fatty acids with 10 to 24 carbon atoms (including unsaturated bonds or branched) and monobasic fatty acids with 2 to 2 carbon atoms 2 Cyclic or polysaccharide reduction such as monovalent, divalent, trivalent, tetravalent, pentavalent, hexavalent alcohol, sorbitan, sorbitol, etc. (which may or may not contain unsaturated bonds) Preferred are mono-fatty acid esters, di-fatty acid esters, and tri-fatty acid esters comprising any one of alcohols and the like, and two or more of these may be used in combination.
  • monobasic fatty acids such as lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, behenic acid, eric acid, and elaidic acid.
  • Fatty acid esters include butyl myristate, butyl palmitate, butyl stearate, neopentyl glycol dioleate, sorbitan monostearate, sorbitan distearate, sorbitan tristearate, oleile oleate, and isolate Cetyl stearate, isotridecyl stearate, octyl stearate, isooctyl stearate, amyl stearate, butoxyshethyl stearate and the like can be mentioned.
  • the total content of these fatty acids and Z or fatty acid esters as lubricants and dispersants appears when the total content is at least 0.1% by weight with respect to the magnetic powder, and the content is increased.
  • the total content exceeds 20% by weight based on the magnetic powder, the total content exceeds 20% by weight and is not completely retained in the magnetic layer and is exposed to the coating film surface, thereby contaminating the magnetic head. , Such as lower output. Therefore, the total content of the fatty acid and Z or fatty acid ester in the magnetic layer is preferably 0.1 to 20% by weight, more preferably 1 to 15% by weight, and still more preferably the magnetic powder. It is 1 to 12% by weight.
  • the lubricant is preferably contained in the back coat layer, the underlayer and the like in addition to the magnetic layer.
  • the magnetic layer when the magnetic layer is thin, it is effective to include the lubricant in the underlayer so that the still durability can be improved.
  • a back coat layer When there is a back coat layer, a large amount of lubricant is contained on the pack coat layer side, and transfer to the surface of the magnetic layer can improve surface lubricity.
  • fatty acids and fatty acids or fatty acid esters need not be 100% pure, and may contain impurities such as isomers, unreacted products, by-products, decomposed products, and oxides in addition to the main components. Absent. However, these impurities are preferably 40% by weight or less, more preferably 20% by weight or less of the entire lubricant.
  • Additives other than the above include those having a lubricating effect, an antistatic effect, a dispersing effect, a plasticizing effect, and the like.
  • the amount of these additives to be added is preferably 10% by weight or less in total with respect to the magnetic powder, particularly preferably 0.01 to 5% by weight.
  • All or some of the fatty acids, fatty acid esters, additives, and the like used in the present invention may be added at any step of the paint production.
  • it may be mixed with the pigment powder before the kneading step, may be added in the kneading step using the pigment powder, the binder and the solvent, may be added in the dispersing step, may be added after the dispersing step, and may be added immediately before application.
  • a solution diluted or dispersed in a solvent may be applied on the coating film.
  • the thickness of the magnetic layer is not particularly limited, and may be appropriately determined according to various conditions such as the recording wavelength. In the case of a single-layer structure, the thickness is preferably 0.5 to 10.0 m, and more preferably. 1.0 to 7.0 / xm. If the magnetic layer is too thin, the strength of the coating film decreases, and the durability tends to deteriorate. If it is too thick, coatability will be poor As the recording wavelength is short, the self-demagnetization loss increases and the overwrite characteristics also deteriorate. As described above, the thickness of the magnetic layer provided as the uppermost layer in the case of a multi-layer structure varies depending on the embodiment, but is preferably from 0.1 to 0.8 ⁇ , more preferably from 0.1 to 0.5 ⁇ . 6 ⁇ .
  • the magnetic layer is too thin, the strength of the coating film decreases, and the durability tends to deteriorate. If the thickness is too large, the coatability deteriorates and the electromagnetic conversion characteristics are liable to deteriorate, and if the recording wavelength is short, the self-demagnetization loss increases and the overwrite characteristics deteriorate.
  • the configuration of this magnetic layer may be substantially the same as the configuration of the uppermost magnetic layer.
  • the non-magnetic inorganic powder in the uppermost magnetic layer mainly plays a role in preventing head clogging, the amount of the non-magnetic inorganic powder in the magnetic layers other than the uppermost layer is minimized in order to suppress the deterioration of electromagnetic conversion characteristics. It is preferable to make the number smaller than that of the upper magnetic layer. Since the non-magnetic inorganic powder in the magnetic layer other than the top layer is mainly added to improve the strength of the coating film, the average particle size is preferably equal to or larger than that added to the top layer. .
  • the thickness of the magnetic layer other than the uppermost layer is preferably from 0.1 to 3.0 Aim, more preferably from 0.3 to 2.5 ⁇ , and still more preferably from 0.5 to 1.5 m. If the magnetic layers other than the top layer are too thin, the surface properties of the non-magnetic support are liable to be affected, and as a result, the surface roughness is deteriorated, and the surface roughness of the top layer is also likely to deteriorate. The characteristics tend to decrease. Also, since the light transmittance is high, there is a problem in detecting the tape end based on the change in the light transmittance. Even if the thickness of the magnetic layer other than the uppermost layer is increased to some extent, the performance is not particularly improved.
  • the nonmagnetic layer provided as a coating film other than the uppermost layer contains at least a nonmagnetic powder and a binder.
  • non-magnetic powders described above can be used as the non-magnetic powder.
  • the binder, solvent, lubricant, additive, and the like used for the nonmagnetic layer may be the same as those used for the magnetic layer described above.
  • the nonmagnetic inorganic powder is preferably used in the range of 50 to 2000% by weight based on the binder, and the nonmagnetic organic powder is preferably used in the range of 0.1 to 20% by weight. %, And the carbon black is preferably 10 to 500% by weight based on the binder.
  • the total content of the fatty acid and / or fatty acid ester as a lubricant in the nonmagnetic layer is preferably 0.01 to 100% by weight based on the binder.
  • the total content of the other additives in the nonmagnetic layer is preferably 0.005 to 50% by weight based on the binder.
  • the thickness of the nonmagnetic layer is preferably from 0.1 to 3.3 ⁇ , more preferably from 0.3 to 2.5 / m, further preferably from 0,5 to: 1.5 / zm. If the non-magnetic layer is too thin, the surface of the non-magnetic support is easily affected, and as a result, the surface roughness of the non-magnetic layer deteriorates, and the surface roughness of the uppermost layer easily deteriorates. Conversion characteristics tend to decrease. In addition, since the light transmittance increases, there is a problem in detecting a tape end based on a change in light transmittance. Even if the nonmagnetic layer is made thicker than a certain level, the performance is not particularly improved.
  • the back coat layer is provided for improving running stability, preventing the magnetic layer from being charged, and the like.
  • the back coat layer preferably contains the above-described carbon black. Carbon black is 10 to 500 It is preferable to use it in the range of weight%. If the content of carbon black is too small, the antistatic effect tends to decrease, and running stability tends to decrease. Also, since the light transmittance tends to be high, there is a problem in the method of detecting the end of the tape by the change in the light transmittance. On the other hand, if the content of carbon black is too large, the strength of the back coat layer decreases, and the running durability tends to deteriorate.
  • the back coat layer may contain, in addition to the carbon black, non-magnetic inorganic powders such as various abrasives mentioned in the description of the magnetic layer in order to increase the mechanical strength.
  • the content of these nonmagnetic inorganic powders is preferably from 0.1 to 5 parts by weight, more preferably from 0.5 to 2 parts by weight, based on 100 parts by weight of the carbon black.
  • the average particle size of the nonmagnetic inorganic powder is preferably about 0.1 to 0.5 ⁇ . If the content of such a nonmagnetic inorganic powder is too small, the mechanical strength of the back coat layer tends to be insufficient, and if it is too large, the amount of abrasion of the guide and the like in the tape sliding path tends to increase.
  • a non-magnetic organic powder is added to the back coat layer, it is preferably used in the range of 0.1 to 20% by weight based on the binder.
  • the binder, the cross-linking agent, the solvent, the lubricant, the additive, and the like used for the back coat layer may be the same as those used for the magnetic layer paint described above. It is preferable that the total content of the fatty acid and the lubricant or the fatty acid ester as the lubricant in the back coat layer is 0.01 to 100% by weight based on the binder. The total content of the other additives in the back coat layer is preferably 0.05 to 50% by weight based on the binder. New
  • the thickness (after calendering) of the back coat layer varies depending on the mode as described above, it is preferably 1.0 m or less, more preferably 0.1 to 1.0 ⁇ m, and still more preferably 0.1 ⁇ m. 2 to 0.8 ⁇ . If the coat layer is too thick, the friction between the medium and the medium sliding path becomes too large, and the running stability tends to decrease. On the other hand, if it is too thin, the surface properties of the backcoat layer will decrease due to the influence of the surface properties of the nonmagnetic support. Therefore, when the back coat layer is thermally cured, the roughness of the back coat layer surface is transferred to the surface of the magnetic layer, resulting in a high-frequency output and a decrease in SZN and CZN. On the other hand, if the back coat layer is too thin, the back coat layer will be shaved during the running of the medium.
  • the step of preparing the coating material for the magnetic layer and the coating material for the non-magnetic layer includes a kneading step of kneading the solid content and the binder solution, a dispersing step of dispersing the solid content in the kneaded material obtained in the kneading step, and A viscosity adjusting step of adding a viscosity adjusting liquid to the dispersion obtained in the dispersion step to obtain a coating material.
  • the step of preparing the coating material for the back coat layer includes a dispersing step of dispersing a solid content in a binder solution, and a viscosity adjusting step of adding a viscosity adjusting liquid to the dispersion obtained in this dispersing step to obtain a coating material.
  • Each step may be divided into two or more stages, and the raw materials may be added in two or more steps.
  • Fig. 1 shows the process of preparing the paint for the magnetic layer and the paint for the non-magnetic layer.
  • a binder solution filtration step (filtration I step), a kneaded material damping step (filtration II step), a dispersion material filtration step (filtration ⁇ step), a viscosity adjusting liquid filtration step (filtration IV step), and Describes the paint pass-through process (Rengo V process).
  • the process of preparing the paint for the back coat layer includes the filtration process of the Pinda solution.
  • Frtration VI step dispersion filtration step
  • filtration VII step viscosity adjustment liquid filtration step
  • Rinpa VIII step viscosity adjustment liquid filtration step
  • Paint filtration step Paint filtration step
  • the binder solution is prepared by dissolving a binder resin in an organic solvent. Ratio of pinda resin to organic solvent, pinda resin organic solvent is weight ratio
  • a filtration I step is provided for the magnetic layer paint and the non-magnetic layer paint
  • a filtration VI step is provided for the back coat layer paint.
  • the binder solution is filtered by a filtration means to remove impurities, gelled binder, undissolved binder, and the like.
  • a kneading step is provided for the magnetic layer paint and the non-magnetic layer paint.
  • a solid content such as a magnetic powder, a non-magnetic powder, and an abrasive is kneaded with a binder solution.
  • the solid content concentration of the kneaded product is preferably 65 to 95% by weight, more preferably 70 to 90% by weight. If the solid content is too low In this case, the viscosity at the time of kneading is too low to obtain a sufficient shearing force, and the solid content is likely to be insufficiently dispersed.
  • the viscosity during kneading becomes too high, making it difficult to obtain an appropriate shear force.
  • a binder solution or an organic solvent is added to dilute the kneaded material to obtain a viscosity suitable for dispersion.
  • the kneading machine can be washed and the yield is improved. It is preferable that the binder solution used for dilution has passed through the filtration I step described above.
  • a filtration II step is provided.
  • solid aggregates and the like in the kneaded material are removed by filtration means.
  • solids such as magnetic powder and non-magnetic powder in the kneaded material are dispersed.
  • solids such as carbon black are kneaded and dispersed with a binder solution.
  • the solid content concentration of the dispersion is preferably 30 to 65% by weight, more preferably 35 to 60% by weight for the coating material for the magnetic layer and the coating material for the non-magnetic layer, and preferably for the coating material for the back coat layer. It is 15 to 45% by weight, more preferably 15 to 40% by weight.
  • the solid content concentration is too low, the viscosity at the time of dispersion becomes low, and the solid content tends to be insufficiently dispersed.
  • the solid content concentration is too high, the viscosity at the time of dispersion becomes too high, and the dispersion of the solid content also tends to be insufficient.
  • a media stirring type disperser such as a sand grinder mill, a pin mill, and an agitator mill.
  • a dispersing medium having a high specific gravity and a ceramic media such as zirconium is suitable, but conventionally used. Glass beads, metal beads, alumina beads, etc. can be selectively used depending on the composition.
  • a coating III step is provided for the coating material for the magnetic layer and the non-magnetic layer
  • a filtration VII step is provided for the coating material for the backcoat layer.
  • the dispersion is filtered by a ripening means to remove undispersed substances and the like, and at the same time, to improve the dispersion of magnetic powder, non-magnetic powder, carbon black and the like.
  • a viscosity adjusting liquid is added to the dispersion and mixed to adjust the viscosity to a preferable value as a paint.
  • the viscosity adjusting liquid uses an organic solvent and Z or a binder solution as a solvent, and preferably uses an organic solvent as a solvent.
  • a lubricant such as a fatty acid or a fatty acid ester is usually dissolved in the solvent to prepare the lubricant.
  • the ratio of the lubricant to the solvent, the lubricant Z solvent is about 0.1 Z100 to 5Z100 by weight. With such a ratio, it is easy to prepare a uniform solution, and the progress of the subsequent filtration step is smooth.
  • the viscosity adjusting liquid is filtered by a filtration means in the filtration IV step for the coating material for the magnetic layer and the coating material for the non-magnetic layer and in the filtration step VII for the coating material for the back coat layer. And filtration Remove contaminants, gelled substances, undissolved substances, etc. as in step VI.
  • the solid content concentration of the coating is preferably 5 to 45% by weight, more preferably 10 to 40% by weight for the coating for the magnetic layer and the coating for the nonmagnetic layer, and is preferably 10 to 40% by weight for the coating for the backcoat layer. It is 8 to 30% by weight, more preferably 10 to 25% by weight. If the solid content is too low or too high, it is difficult to form a uniform coating film.
  • a filtration V step is provided for the magnetic layer paint and the non-magnetic layer paint
  • a pass IX step is provided for the back coat layer paint.
  • the paint is filtered by a ripening means to remove magnetic powder, non-magnetic powder, aggregates such as carbon black, and undispersed substances.
  • the paint prepared in this manner is a stock paint.
  • a curing agent is added before application to make a final paint, and this final paint is supplied to the application process.
  • a filtration X step is provided for the magnetic layer paint and non-magnetic layer paint
  • a filtration XI step is provided for the back coat layer paint.
  • the addition of a curing agent may cause the dispersion state of the particles in the paint to fluctuate, causing agglomerates.Therefore, the filtration X step and the filtration XI step occurred after the filtration V step and the filtration IX step, respectively. Provided to remove agglomerates.
  • the pressure applied to the paint in step X and filtration XI is controlled so that the amount of paint supplied to the coating machine is constant.
  • the coating material is generally applied to a long film-shaped non-magnetic support drawn out from an unwinding roll by various known coating means such as a gravure coat, a reverse roll coat, and an extrusion nozzle coat.
  • the non-magnetic substrate before coating is coated with wet cleaning using water or a solvent, for the purpose of cleaning and surface adjustment, dry cleaning using non-woven fabric or ultra-fine fiber fabric, etc. as a wiper, compressed air
  • the treatment is carried out by various known means such as non-contact type cleaning using vacuum, vacuum, ionized air and the like.
  • various known non-contact surface treatments such as corona discharge, ultraviolet irradiation, and electron beam irradiation are performed for the purpose of improving the adhesion between the paint and the non-magnetic support and modifying the coated surface. Often.
  • an undercoat such as a water-based undercoat, an emulsion-based undercoat, or a solvent-based undercoat may be performed in combination with the surface treatment described above or alone.
  • an undercoat layer may be formed by applying a coating material in which a nonmagnetic inorganic pigment or organic pigment is dispersed in a binder, or may be used in combination with the surface treatment described above.
  • various processes such as ⁇ smoothing of the jet film surface of the magnetic coating material provided on the non-magnetic support ⁇ and the regulation of the coating film may be performed.
  • the smoothing means known methods such as non-contact methods such as contacting a resin, metal, ceramics film or par with a magnetic field by a permanent magnet, an electromagnet, or the like, or vibration by an ultrasonic wave can be used. They can be used alone or in combination depending on the required characteristics.
  • the magnetic layer After the magnetic layer is formed, it is necessary to apply a magnetic field to orient the magnetic particles in the layer, regardless of whether the orientation direction is the longitudinal direction of the medium or the perpendicular direction. It may be in an oblique direction. In order to orient in a predetermined direction, it is preferable to apply a magnetic field of 100 G or more using permanent magnets such as funilite magnets or rare earth magnets, electromagnets, solenoids, or the like alone or in combination. Furthermore, a process of drying appropriately before the orientation may be provided so that the orientation after drying is the highest, or drying may be performed at the same time as the orientation.
  • the oriented magnetic powder may be in a non-oriented state as far as possible with a permanent magnet, an electromagnet, a solenoid, or the like.
  • the magnetic coating film that has been subjected to the post-coating treatment in this manner is usually heated by a known drying and evaporating means such as hot air, far-infrared rays, an electric heater, a vacuum device provided in a drying furnace or the like, or ultraviolet rays. It is dried and fixed by a known curing device such as a Rambe radiation irradiation device. Drying temperature from room temperature The temperature may be appropriately determined in the range up to about 300 ° C. depending on the heat resistance of the nonmagnetic support, the solvent type, the concentration, and the like. Note that a temperature gradient may be provided in the drying furnace. General air or inert gas may be used as the atmosphere gas in the drying furnace.
  • drying When drying is performed by an ultraviolet lamp or a radiation irradiation device, a curing reaction occurs. Therefore, when post-processing is considered, it is preferable to use other drying means as much as possible. Irradiation with ultraviolet rays or radiation while containing a solvent may cause ignition or smoking, and in this case, it is preferable to use or use other drying means as much as possible.
  • a calendar process is performed as a surface smoothing process as needed.
  • calendering rolls include heat-resistant plastic rolls such as epoxy, polyester, nylon, polyimide, polyamide, and polyimide (which may be kneaded with carbon, metal, or other inorganic compounds) and metals.
  • a combination with a roll (combination of 3 to 7 stages) or a combination of only metal rolls may be used.
  • the processing temperature of the calendaring is preferably 70 or more, more preferably 80 ° C or more, and the linear pressure is preferably 20 Okg / cm or more, more preferably 300 kg / cm or more.
  • the processing speed is preferably in the range of 20 to 700 mZ.
  • the magnetic layer, a back coat layer, in order to accelerate the cure of the non-magnetic layer may be subjected to 4 0-8 0 thermosetting treatment and Z or electron beam irradiation treatment at e C.
  • the magnetic recording medium is processed into a predetermined shape and further subjected to secondary processing to obtain a magnetic recording medium.
  • a filtration means including the following final filtration means is used.
  • the filtration means has a 95% cut filtration accuracy of 4.0 ⁇ or more, and the final filtration means used in the filtration IV step and filtration VIII step of filtering the viscosity adjusting liquid has a 95% cut filtration accuracy of 1%. 0 ⁇ or more.
  • the final filtration means used in the filtration step of the Pinda solution has a 95% power filtration accuracy of 80 fm or less, preferably 75 ⁇ or less.
  • the 5% cut filtration accuracy must be 30 urn or less, preferably 15 m or less, and at least one of the conditions must be satisfied.
  • the final filtration means used in the V step has a 95% cut filtration accuracy of 10 times or less of the shortest recording wavelength, 6.0 ⁇ or less, and 1.0 Z / m or more, preferably the shortest.
  • the 95% cut filtration accuracy is 1.0 to 6.0 mm, preferably 1.0 to 5.0 m.
  • the final filtration means used in the filtration IX step which filters the coating for the back coat layer, has a 95% cut accuracy of 1.0 Aim or more and 6.0 m or less and a thickness of the back coat layer of 1 m or less. 0 times or less, preferably 1.0 xm or more and 6.0 ⁇ or less and 9 times or less the thickness of the pack coat layer.
  • the final filtration means used in the filtration II step of filtering the kneaded material and in the filtration step III and the filtration step VII of filtering the dispersion have a 95% cut accuracy of 15 / zm or more.
  • the 95% cut filtration accuracy of the final filtration means in at least one of the filtration II step and the filtration III step and the filtration step VII must be 80 Atm or less, preferably 75 tm or less.
  • Table 1 shows specific examples of the shortest recording wavelength for each recording method. Table 1 Method (analog)
  • the shortest recording wavelength in the analog video recording method shown in Table 1 is (relative speed of the recording medium with respect to the recording head) / (white peak frequency), and the shortest recording wavelength in the digital video recording method is , (Relative speed of the recording medium with respect to the recording head) / ⁇ (transmission rate) X (1Z2) X (the number of tracks per scan) ⁇ .
  • the effect of trapping the capture target will be saturated, and in the filtration V step, the filtration II step and the ⁇ 1 filtration step III ⁇ , The abrasive particles that need to pass through the filtration means are trapped by the filtration means, making it impossible to increase the mechanical strength of the coating film.
  • the filtration step VII and the filtration step IX Conductive pigments and non-magnetic inorganic powder particles that need to pass through the filtration means are captured by the filtration means, making it impossible to increase the conductivity and mechanical strength of the pack coat layer.
  • the 95% cut-off accuracy of the pass-through means is obtained by the following method using, for example, the apparatus shown in FIG.
  • test dust (8 or 11 types specified in JISZ8901) into the undiluted solution tank 101 and stir to obtain undiluted solution.
  • 95% cut filtration accuracy of the filtration means to be measured is 10 Aim or less, use 11 kinds of test dust, and when it exceeds 10 Atm, use 8 kinds.
  • Pressurize with the bomb P circulate the stock solution in the direction shown by the arrow, and continuously filter it with the thigh means (filter F). At this time, the pressurized amount of the bomb is controlled while monitoring with the flow meter 102 so that the circulating flow rate of the stock solution is 40 liters Z minutes.
  • the depth filter is a filter having a large volume filter and usually has a structure in which a cylindrical filter medium is housed in a housing.
  • the material of the deb filter is a sponge formed by forming three-dimensional mesh-like pores in a resin such as PVA, or a resin fiber such as polypropylene or a glass fiber wound, and the wound. Fibers fixed with resin pinda, beads bonded, etc. are used.
  • the ⁇ 1 direction of the depth filter is generally the direction from the outer circumference to the inner circumference, and is usually provided with a density gradient in which the hole diameter gradually decreases or gradually decreases from the outer circumference to the inner circumference. ing. This density gradient is intended to improve the fill life. You.
  • various commercially available debasfills can be used.
  • a filter having a 95% power filtration accuracy determined by the above method within the scope of the present invention may be selected from various commercially available filters and used. it can.
  • Kanebo Co., Ltd.'s Debs type cartridge filters (Riki Nefil R series, RS series, and RP series) and Loki Techno Co., Ltd.'s ultra-type HT type ultra filter, etc. It is preferable to select one having the desired 95% power transmission accuracy.
  • the conditions other than the 95% cut precision are not particularly limited, but the pressure applied to the workpiece is preferably 0.5 to 10 kg / cm 2 , and the pressure loss is preferably It is preferably at most 5 kg / cm 2 .
  • the filter F provided in the middle of the flow path 202 of the material to be filtered communicating with the tank 201 is usually used as the above-mentioned final filtration means.
  • the material to be filtered is passed through a pump P provided on the upstream side of the filter F, and the present invention is applied to at least one of these filtering steps in the above-described multi-stage S filter. It is preferable to carry out the combination of parallel filtration and circulation filtration as appropriate.
  • the 95% cut filtration accuracy is higher than the final filtration means upstream of the final filtration means.
  • a large filtering means is arranged, it is preferable to arrange each filtering means so that the 95% cut filtration accuracy gradually decreases from the upstream side to the downstream side of the flow path.
  • the 95% cut filtration accuracy of the filtration means located upstream of the final filtration means is preferably 20 times or less, more preferably 10 times, the 95% cut filtration accuracy of the final filtration means. Below and 1.5 times or more.
  • FIG. 5 shows a specific example of such multi-stage filtration.
  • three filters F are provided in series with the flow path 202 so that the 95% cut accuracy gradually decreases from the upstream side to the downstream side.
  • the multi-stage filtration is preferably performed in three or more stages, but the multi-stage filtration in six or more stages is not preferable because the productivity is reduced.
  • a parallel filtering unit configured by arranging a plurality of filters in a channel in parallel is used.
  • the parallel filtering means may have a configuration in which a plurality of filters are accommodated in a single housing, or a configuration in which a plurality of housings each accommodating one filter are arranged.
  • Fig. 6 shows a specific example of parallel filtration.
  • three filters F are provided in parallel with the flow path 202 and constitute the parallel transmission means 203.
  • the number of filters constituting the parallel filtration means is not particularly limited, and may be appropriately determined according to various conditions such as a filtration area per one filter and a required flow rate.
  • Parallel filtration may be used in conjunction with the multi-stage filtration described above. In this case, usually all the filtration means are parallel filtration means, but only some of the filtration means may be parallel filtration means.
  • FIG. 7 shows a specific example in which parallel filtration and multi-stage filtration are used in combination.
  • three parallel transmission means 203 are provided in series with the flow path 202.
  • the flow path 202 is branched upstream of the parallel filtration means, and the flow paths are assembled after the object to be processed has passed through all the parallel filtration means.
  • the configuration may be such that the flow path branches and aggregates for each parallel transmission means.
  • Fig. 8 shows a specific example of circulation passage.
  • the tank The material to be filtered that has reached the three-way valve 204 from the filter 201 through the filter F is returned to the tank 201 through the circulation passage 205.
  • the three-way valve 204 is operated so as to shut off the outlet to the circulation channel 205.
  • the number of circulations is not particularly limited, and may be set appropriately according to the supply amount of the substance to be filtered to the next step, the tank capacity, and the like.
  • the circulation filtration is preferably used in combination with the above-described multi-stage filtration or parallel filtration, and most preferably in combination with both the multi-stage filtration and the parallel filtration.
  • Specific examples using both circulation filtration and multi-stage filtration are shown in FIGS. 9 to 11, respectively.
  • FIG. 9 in the three-stage multistage filtration, each stage of filtration is circulated.
  • Fig. 10 in the three-stage multistage filtration, the first stage is circulating filtration, followed by two-stage multistage filtration.
  • Fig. 11 in the three-stage multistage filtration, the circulation filtration is performed after the two-stage multistage filtration. Which of the configurations shown in FIGS.
  • FIGS. 9 to 11 should be selected may be appropriately determined according to the supply amount of the material to be filtered to the next step, the capacity of the tank, and the like.
  • the filtration accuracy is good, and dispersion is particularly good in each of the filtration II, filtration III, filtration V, filtration VII, and filtration IX steps. It is preferred.
  • a configuration other than those shown in FIGS. 9 to 11 may be adopted by combining the circulation filtration and the multi-stage filtration.
  • Filtration means other than the final filtration means limited in each embodiment is not particularly limited, and a filter having a pore diameter according to each purpose may be appropriately selected and used.
  • a final filtration means having a 95% cut accuracy equivalent to the final filtration means used in the filtration V step in the filtration step X and a filtration IX in the filtration step XI.
  • a final filtration means having 95% cut filtration accuracy equivalent to the final filtration means used in the process In the other filtration steps, the multi-stage filtration, the parallel filtration, and the circulation filtration described above may be performed.
  • the method of applying the coating material prepared as described above to the nonmagnetic support there is no particular limitation on the method of applying the coating material prepared as described above to the nonmagnetic support, and any method that is commonly used may be used.
  • a so-called “jet-on-jet” coating method in which a lower layer and an upper layer are coated in a wet state on a non-magnetic support, or a lower layer is coated.
  • Any of the so-called “jet-on” and “dry-coating” methods of applying the upper layer after drying can be used, but the wet-on-jet-coating method is preferably used.
  • the application of the pack coat layer may be performed before or after the application of the lower layer and the upper layer, or at the same time.
  • an underlayer made of a nonmagnetic material is provided between the nonmagnetic support and the lowermost coating film for the purpose of improving surface properties, improving adhesion, improving durability, and the like. You may. Further, a protective lubricating layer such as a lubricant layer, a plasma polymerized film, or a diamond-like film may be provided on the magnetic layer in order to lubricate and protect the magnetic layer.
  • BC layer the back coat layer.
  • composition was added to the slurry after kneading to adjust the viscosity to be optimal for dispersion treatment;>
  • the slurry was filtered with a filter.
  • the slurry after the filtration was subjected to a dispersion treatment using a sand mill.
  • the slurry after the dispersion treatment was filtered by a filter for 3 ⁇ 4 seconds.
  • the following composition was put into a hypermixer, mixed and stirred for 1 hour to obtain a viscosity adjusting liquid.
  • the viscosity adjusting solution was passed through the filter.
  • the paint was leaked through the filter.
  • 0.8 parts by weight of an isocyanate compound manufactured by Nippon Polyurethane Industry Co., Ltd., Koguchinate L
  • a final coating material for the magnetic layer was obtained in the same manner as the coating material for the upper layer, except that the composition used in the kneading step was as described above.
  • a final paint for the non-magnetic layer was obtained in the same manner as the paint for the upper layer except that the composition used in the kneading step was as follows.
  • the binder solution was passed through a filter.
  • the following composition was charged into a ball mill and dispersed for 24 hours.
  • the slurry after the dispersion treatment was passed through a filter.
  • the following composition was put into a hyper mixer, mixed for 1 hour, and stirred to obtain a viscosity adjusting liquid.
  • One hundred parts by weight of the paint after passing was mixed with 1 part by weight of an isocyanate compound (Coronate L, manufactured by Nippon Polyurethane Industry Co., Ltd.) and stirred to obtain a final paint for the backcoat layer.
  • an isocyanate compound (Coronate L, manufactured by Nippon Polyurethane Industry Co., Ltd.)
  • each table shows the 95% cut filtration accuracy of the filter used in each filtration step.
  • the material of the Debs filter having a 95% cut filtration accuracy of 15.0 m or more is a cylindrical material obtained by applying a melamine resin treatment to a sponge-like PVA resin having three-dimensional mesh-like pores.
  • a Debss filter having a 95% cut filtration accuracy of less than 15.0 ⁇ overlaps a small-diameter cylindrical filter medium and a large-diameter cylindrical filter medium made of boropropylene, respectively, and filters these filters.
  • a filter member made of glass fiber is provided between the members.
  • Table 4 in this example shows the sample prepared without multi-stage filtration. Nos. 1 and 2 are also shown for comparison.
  • the calender roll used was a 7-stage combination of a heat-resistant plastic roll and a metal roll. The metal roll was in contact with the coating film, and the processing temperature was 100 * 0 and the linear pressure was 250 kg. / cm 2. The degree of contamination of the metal roll after treating the magnetic layer surface with 200,000 meters was evaluated according to the following criteria.
  • the back surface of the non-magnetic support was coated with a paint for a back coat layer, dried, and similarly calendered.
  • the coating material for the coating film on the nonmagnetic support surface side was subjected to filtration immediately before application in the filtration X step.
  • a filter with the same 95% cut filtration accuracy as the filter used in each filtration V step was used.
  • the coating for the backcoat layer passed 1 step immediately before application in the step XI.
  • step XI a filter having the same 95% cut filtration accuracy as the filter used in step IX was used. After each coating was cured, it was cut into 8 mm widths and assembled into cassettes to form magnetic tape samples. The thickness of the upper layer, lower layer and back coat layer after curing is shown in each table.
  • Dropout (DO) was measured for each sample. In this measurement, drop when the output decrease of 16 dB or more continues for 15 PLS or more. It was determined to be a breakout. The measurement was performed for 10 minutes, and each table shows the dro and jib-out per minute. For the measurement, a Sony EV-S900 (8 marauding format VTR) was used.
  • the effect of independently performing the kneading step and the dispersing step in the preparation step of the coating material for the magnetic layer was examined.
  • dilution is performed to adjust the concentration, and then dispersed.
  • the binder solution after the filtration I and the following composition were charged into a ball mill so as to have a concentration after dilution from the beginning, and mixed and dispersed for 24 hours to obtain a dispersion.
  • a final paint was obtained in the same manner as the paint for the upper layer in Example 1.
  • a final paint was obtained in the same manner as in the pack coat layer paint of Example 1.
  • Dropout (DO) was measured for each sample. At the time of this measurement, a case where the output decrease of 16 dB or more continued for 15 ⁇ or more was determined as a drop. The measurement was performed for 10 minutes, and each table shows the drop rate per minute.
  • Sony EV-S 900 Hi 8 format VTR
  • JVC BR-S711 S-VHS format VTR
  • JVC BR-7000 VHS Format VTR. The measurement format and the shortest recording wavelength are shown in each table.
  • a final paint was obtained in the same manner as the paint for the upper layer in Example 1.
  • a final paint was obtained in the same manner as the paint for magnetic layer (composition II) of Example 2.
  • a final paint was obtained in the same manner as in the paint for magnetic layer (composition 3) in Example 2.
  • a final paint was obtained in the same manner as in Example 1 for the lower layer paint (for the magnetic layer).
  • a final paint was obtained in the same manner as in Example 1 for the lower layer paint (for the non-magnetic layer).
  • Dropout (DO) was measured for each sample. In this measurement, a drop-out was determined when the output decrease of 12 dB or more continued for 10 / S or more. The measurement was performed for 10 minutes, and each table shows the dropout per minute. Measurements were performed using Sony EV-S 900 (Hi 8 format VTR), JVC BR-S711 (S-VHS format VTR), JVC BR-7000 (VHS format). VTR). The measurement format and the shortest recording wavelength are shown in each table.
  • the filtration IX step in the preparation of the paint for the pad coat layer included the ninth aspect of the present invention.
  • the ⁇ sample with parallel filtration and circulating filtration J performed better than the comparison sample with a filter with a 95% cut filtration accuracy outside the range of the present invention. It can be seen that the dropout is remarkably small and a high effect can be obtained, and that multi-stage filtration further reduces the dropout. If a filter with a filtration accuracy of 0.8 m is used, the pressure loss will be 1 O kg / cm 2 or more, and it will not be possible to apply paint.
  • a final paint was obtained in the same manner as the paint for the upper layer in Example 1.
  • a final paint was obtained in the same manner as the paint for magnetic layer (composition II) of Example 2.
  • a final paint was obtained in the same manner as in the paint for magnetic layer (composition 3) in Example 2.
  • a final paint was obtained in the same manner as in Example 1 for the lower layer paint (for the magnetic layer).
  • a final paint was obtained in the same manner as in Example 1 for the lower layer paint (for the non-magnetic layer).
  • Dropout (DO) was measured for each sample. In this measurement, a case where the output decrease of 1 OdB or more continued for 5 js or more was determined as a drop fault. The measurement was performed for 10 minutes, and each table shows the dropout per minute. Measurements were made using Sony's EV-S 900 (Hi--8 format VTR), JVC BR-S711 (S-VHS format VTR), JVC's BR-7000 (VHS format). VTR). The measurement format and the shortest recording wavelength are shown in each table.
  • the 95% cut-off accuracy is 95%.
  • the occurrence of drop drops is extremely small even under an extremely severe slice level. If a filter with a 95% cut filtration accuracy of 8.0 m was used in the filtration II and III steps, the pressure loss would be 10 kg / cm 2 or more, and the coating would not be made. It was possible.
  • a final paint was obtained in the same manner as the paint for the upper layer in Example 1.
  • a final paint was obtained in the same manner as the paint for magnetic layer (composition II) of Example 2.
  • a final paint was obtained in the same manner as in the paint for magnetic layer (composition 3) in Example 2.
  • a final paint was obtained in the same manner as in Example 1 for the lower layer paint (for the magnetic layer).
  • a final paint was obtained in the same manner as in Example 1 for the lower layer paint (for the non-magnetic layer).
  • Dropout (DO) was measured for each sample. At the time of this measurement, when the output decreased by 1 OdB or more continued for 5 S or more, it was determined to be a mud or a jib out.
  • the measurement is performed on the sample immediately after preparation and on the sample after storage for 5 days in a 50-C80 RH environment, and after standing for 24 hours in a 20 ° C60% RH environment (after storage at high temperature and high humidity) for 10 minutes.
  • Each table shows the dropout per minute for the sample after storage.
  • Sony's EV-S900 Hi--8 format VTR
  • JVC BR-S711 S-VHS format VTR
  • JVC BR-700 0 VHS format VTR
  • BC layer 0.5 0.5 ai (by night) 5.0 5.0 5.0 Upper leg ⁇ ⁇ ) 15.0 15.0 mm (min) 15.0 15.0 listen V (viscosity adjusting solution) 1.2 1.2 Filtration V (after adjusting viscosity) 1.2 1.2 Leakage I (binter Solution) 5.0 5.0 lower 3 ⁇ 43 ⁇ 4 ⁇ 3 ⁇ 4 ⁇ (after kneading) 15.0 15.0 lake m (separation 15.0 15.0 over IV (viscosity adjusting solution) 1.2 1.2 over V (after viscosity adjusting) 15.0 15.0
  • the level of dropout after storage under high temperature and humidity was not different from the level of dropout immediately after production, and there was almost no deterioration in characteristics due to storage.
  • the comparative sample it was at a level without any problem immediately after fabrication, but the deterioration due to storage was remarkable.
  • a filter with a filtration accuracy of less than 95% is used for filtration I and filtration VI
  • a filter with a filtration accuracy of less than 4 ⁇ is used, as well as filtration IV and filtration VIII.
  • a final paint was obtained in the same manner as in Example 1 for the lower layer paint (for the magnetic layer). .
  • a final paint was obtained in the same manner as in Example 1 for the lower layer paint (for the non-magnetic layer).
  • Dropout (DO) measurements were made for each sample. Measurements were taken on the sample immediately after preparation and on the sample after storage at high temperature and high humidity (stored in a 50 ° C / 80% RH environment for 5 days, then left in a 20 * C / 60% RH environment for 24 hours). Was. In this measurement, when the output reduction power s was more than 16 dB and continued for more than 15 s, it was judged as dropout. The measurement was performed for 10 minutes, and each table shows the dropout per minute of the sample after storage at high temperature and high humidity. A Sony EV-S 900 (8 difficult format VTR) was used for the measurement.
  • a final paint was obtained in the same manner as the paint for the upper layer in Example 1.
  • a final paint was obtained in the same manner as in Example 1 for the lower layer paint (for the magnetic layer).
  • a final paint was obtained in the same manner as in Example 1 for the lower layer paint (for the non-magnetic layer).
  • the magnetic tapes A mumble was prepared.
  • the degree of contamination of the back coat layer-side force render roll after the force render treatment is shown in each table.
  • Drop sample (DO) measurements were performed for each sample. Measurements and Samburu immediately after production (after 50 e C ⁇ 80% RH environment for 5 days storage, under 2 0 e C ⁇ 60% RH environment for 24 hours standing) after being stored at high temperature and high humidity for a Sun Bull Done. At the time of this measurement, a case where the output decrease of 12 dB or more continued for 1 OS or more was determined as a drop fault. The measurement was performed for 10 minutes, and each table shows the dropout per minute of the sample after the high-temperature and high-humidity storage. For the measurement, Sony EV-S900 (Hi8 format VTR) was used.
  • the D 0 immediately after the preparation is small but high temperature.
  • the final paint was obtained in the same manner as in Example 1 for the lower layer paint (for the non-magnetic layer).
  • Each of the above paints was applied, and magnetic tape samples shown in each table were produced in the same manner as in the above examples.
  • Each table shows the degree of contamination of the magnetic layer side render roll after the calendering treatment.
  • Drop samples (DO) were measured for each sample. The measurements were performed on the sample immediately after preparation and on the sample after storage at high temperature and high humidity (stored in a 50 ⁇ 80% RH environment for 5 days, then left in a 20 * 0 ⁇ 60% RH environment for 24 hours). In this measurement, a case where the output decrease of 10 dB or more continued for 5 S or more was determined to be a drop fault. The measurement was performed for 10 minutes, and each table shows the dropout per minute of the sample after storage at high temperature and high humidity. For the measurement, Sony EV-S 900 (Hi 8 format VTR) was used.
  • the pressure loss is 10 kg / cm in all cases. 2 or more, making it impossible to paint.
  • a final paint was obtained in the same manner as the paint for the upper layer in Example 1.
  • a final paint was obtained in the same manner as in Example 1 for the lower layer paint (for the non-magnetic layer). .
  • Dropout (DO) measurements were made for each sample. Measurements and Samburu immediately after production, (after storage under 50 e C ⁇ 80% RH environment for 5 days, under 20 * C ⁇ 60% RH environment for 24 hours standing) after storage ⁇ high humidity for a sample of Done. In this measurement, when the output decreased by 10 dB or more continued for 5 s or more, it was judged as dropout. The measurement was performed for 10 minutes, and each table shows the dropout per minute of the sample after storage at high temperature and high humidity. For the measurement, Sony EV-S 900 (Hi 8 format VTR) was used.
  • a comparison sample using a filter having a filtration accuracy exceeding 95% in the range of the present invention and a filtration V step were used.
  • the storage under high-temperature and high-humidity conditions significantly deteriorates Y—C / N.
  • D 0 immediately after the preparation was small, but D 0 slightly increased due to high-temperature and high-humidity storage.

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  • Chemical & Material Sciences (AREA)
  • Dispersion Chemistry (AREA)
  • Application Of Or Painting With Fluid Materials (AREA)
  • Manufacturing Of Magnetic Record Carriers (AREA)

Abstract

Le premier objet de la présente invention est de permettre l'obtention d'un support d'enregistrement magnétique présentant, juste après sa production, moins d'irrégularités entraînant des pertes de niveau, dont les irrégularités entraînant des pertes de niveau n'augmentent pas avec le temps, dont les propriétés de conversion électromagnétique ne s'altèrent pas, et qui est pourvu d'un revêtement de grande durabilité, tel qu'une couche magnétique. Le deuxième objet de la présente invention est de permettre l'obtention d'un support d'enregistrement magnétique pourvu d'une couche dorsale de grande durabilité, cette couche empêchant efficacement une accumulation de charge, cela en plus des caractéristiques concernées par le premier objet de l'invention. Le troisième objet de la présente invention est d'améliorer la productivité et de réduire les coûts en ce qui concerne la production d'un tel support d'enregistrement magnétique. Selon un procédé de production comprenant une étape consistant à malaxer un matériau solide et une solution de liant, une étape consistant à mettre en suspension un matériau solide dans le produit malaxé, et une étape consistant à ajouter une solution d'ajustement de la viscosité à la dispersion pour obtenir un matériau de revêtement, les matériaux (solution de liant, matériau malaxé, dispersion, agent d'ajustement de la viscosité, matériau de revêtement) sont filtrés après chaque étape décrite ci-dessus, et un dispositif pouvant effectuer une filtration de 95 %, par rapport à une plage de valeurs prédéterminée, est utilisé à chaque étape de filtration.
PCT/JP1994/002014 1993-12-01 1994-11-30 Procede de production d'un support d'enregistrement magnetique WO1995015556A1 (fr)

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KR1019950703009A KR100283522B1 (ko) 1993-12-01 1994-11-30 자기기록매체의 제조방법
DE69432923T DE69432923T2 (de) 1993-12-01 1994-11-30 Verfahren zur produktion eines magnetischen aufzeichnungsmediums
EP95902279A EP0684597B1 (fr) 1993-12-01 1994-11-30 Procede de production d'un support d'enregistrement magnetique

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JP34181993 1993-12-13
JP5/341819 1993-12-13
JP34625193 1993-12-22
JP5/346251 1993-12-22
JP6/52738 1994-02-25
JP6/52736 1994-02-25
JP5273894 1994-02-25
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EP0684597A4 (fr) 1996-05-22
EP0684597B1 (fr) 2003-07-09
EP1246172A1 (fr) 2002-10-02
EP1246170A1 (fr) 2002-10-02
EP0684597A1 (fr) 1995-11-29
KR100283522B1 (ko) 2001-03-02
DE69432923D1 (de) 2003-08-14
DE69432923T2 (de) 2004-05-19
US5510140A (en) 1996-04-23
KR960700504A (ko) 1996-01-20
EP1246171A1 (fr) 2002-10-02

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